Exhibit 4.14

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                                      FORM

                                       OF

                    PREFERRED SECURITIES GUARANTEE AGREEMENT


                         MCKESSON FINANCING TRUST III



                               Dated as of [  ]

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                               TABLE OF CONTENTS


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                                                                                               ----
                                                                                          

                                   ARTICLE I

                         DEFINITIONS AND INTERPRETATION

SECTION 1.1  Definitions and Interpretation...................................................   1


                                   ARTICLE II

                              TRUST INDENTURE ACT

SECTION 2.1  Trust Indenture Act; Application.................................................   4
SECTION 2.2  Lists of Holders.................................................................   4
SECTION 2.3  Reports by the Preferred Guarantee Trustee.......................................   4
SECTION 2.4  Periodic Reports to Preferred Guarantee Trustee..................................   5
SECTION 2.5  Evidence of Compliance with Conditions Precedent.................................   5
SECTION 2.6  Events of Default; Waiver........................................................   5
SECTION 2.7  Event of Default; Notice.........................................................   5
SECTION 2.8  Conflicting Interests............................................................   6

                                  ARTICLE III

            POWERS, DUTIES AND RIGHTS OF PREFERRED GUARANTEE TRUSTEE

SECTION 3.1  Powers and Duties of the Preferred Guarantee Trustee.............................   6
SECTION 3.2  Certain Rights of Preferred Guarantee Trustee....................................   7
SECTION 3.3  Not Responsible for Recitals or Issuance of Preferred Securities Guarantee.......   9

                                   ARTICLE IV

                          PREFERRED GUARANTEE TRUSTEE

SECTION 4.1  Preferred Guarantee Trustee: Eligibility.........................................  10
SECTION 4.2  Appointment, Removal and Resignation of Preferred Guarantee Trustee..............  10
 

                                      ii

 
 
                                                                                            

                                   ARTICLE V

                                   GUARANTEE

SECTION 5.1  Guarantee........................................................................  11
SECTION 5.2  Waiver of Notice and Demand......................................................  11
SECTION 5.3  Obligations Not Affected.........................................................  12
SECTION 5.4  Rights of Holders................................................................  12
SECTION 5.5  Guarantee of Payment.............................................................  13
SECTION 5.6  Subrogation......................................................................  13
SECTION 5.7  Independent Obligations..........................................................  13


                                   ARTICLE VI

                   LIMITATION OF TRANSACTIONS; SUBORDINATION

SECTION 6.1  Limitation of Transactions.......................................................  13
SECTION 6.2  Subordination....................................................................  14


                                  ARTICLE VII

                                  TERMINATION

SECTION 7.1  Termination......................................................................  14


                                  ARTICLE VIII

                                INDEMNIFICATION

SECTION 8.1  Exculpation......................................................................  15
SECTION 8.2  Indemnification..................................................................  15


                                   ARTICLE IX

                                 MISCELLANEOUS

SECTION 9.1  Successors and Assigns...........................................................  16
SECTION 9.2  Amendments.......................................................................  16
SECTION 9.3  Notices..........................................................................  16
SECTION 9.4  Benefit..........................................................................  17
SECTION 9.5  Governing Law....................................................................  17


                                      iii

 

                    PREFERRED SECURITIES GUARANTEE AGREEMENT

     This GUARANTEE AGREEMENT (the "Preferred Securities Guarantee"), dated as
of    [          ], is executed and delivered by McKesson Corporation, a
Delaware corporation (the "Guarantor"), and [             ], as trustee (the
"Preferred Guarantee Trustee"), for the benefit of the Holders (as defined
herein) from time to time of the Preferred Securities (as defined herein) of
McKesson Financing Trust III, a Delaware statutory business trust (the
"Issuer").

     WHEREAS, pursuant to an Amended and Restated  Declaration of Trust (the
"Declaration"), dated as of [             ], among the trustees of the Issuer
named therein, the Guarantor, as sponsor, and the holders from time to time of
undivided beneficial interests in the assets of the Issuer, the Issuer is
issuing on the date hereof up to [             ] preferred securities (the
"Preferred Securities"), having a liquidation amount of $[  ] per Preferred
Security designated the [            ] Preferred Securities.

     WHEREAS, as incentive for the Holders to purchase the Preferred Securities,
the Guarantor desires irrevocably and unconditionally to agree, to the extent
set forth in this Preferred Securities Guarantee, to pay to the Holders of the
Preferred Securities the Guarantee Payments (as defined herein) and to make
certain other payments on the terms and conditions set forth herein.

     WHEREAS, as of the date hereof, the Guarantor is also executing and
delivering a guarantee agreement (the "Common Securities Guarantee") in
substantially identical terms to this Preferred Securities Guarantee for the
benefit of the holders of the Common Securities (as defined herein), except that
if an Event of Default (as defined in the Indenture) has occurred and is
continuing, the rights of holders of the Common Securities to receive Guarantee
Payments under the Common Securities Guarantee are subordinated to the rights of
Holders of Preferred Securities to receive Guarantee Payments under this
Preferred Securities Guarantee.

     NOW, THEREFORE, in consideration of the purchase by each Holder of
Preferred Securities, which purchase the Guarantor hereby agrees shall benefit
the Guarantor, the Guarantor executes and delivers this Preferred Securities
Guarantee for the benefit of the Holders.


                                   ARTICLE I

                         DEFINITIONS AND INTERPRETATION

      SECTION 1.1  Definitions and Interpretation.

     In this Preferred Securities Guarantee, unless the context otherwise
requires:

     (a) Capitalized terms used in this Preferred Securities Guarantee but not
defined in the preamble above have the respective meanings assigned to them in
this Section 1.1;

                                       1

 
     (b) terms defined in the Declaration as at the date of execution of this
Preferred Securities Guarantee have the same meaning when used in this Preferred
Securities Guarantee unless otherwise defined in this Preferred Securities
Guarantee;

     (c) a term defined anywhere in this Preferred Securities Guarantee has the
same meaning throughout;

     (d) all references to "the Preferred Securities Guarantee" or "this
Preferred Securities Guarantee" are to this Preferred Securities Guarantee as
modified, supplemented or amended from time to time;

     (e) all references in this Preferred Securities Guarantee to Articles and
Sections are to Articles and Sections of this Preferred Securities Guarantee,
unless otherwise specified; a term defined in the Trust Indenture Act has the
same meaning when used in this Preferred Securities Guarantee, unless otherwise
defined in this Preferred Securities Guarantee or unless the context otherwise
requires; and

     (f) a reference to the singular includes the plural and vice versa.

     "Authorized Officer" of a Person means any Person that is authorized to
legally bind such Person provided, however, that the Authorized Officer signing
an Officers' Certificate given pursuant to Section 314(a)(4) of the Trust
Indenture Act shall be the principal executive, financial or accounting officer
of such Person.

     "Common Securities" means the securities representing common undivided
beneficial interests in the assets of the Issuer.

     "Corporate Trust Office" means the office of the Preferred Guarantee
Trustee at which the corporate trust business of the Preferred Guarantee Trustee
shall, at any particular time, be principally administered, which office at the
date of execution of this Agreement is located at [           ], Attention: 
[       ].

     "Covered Person" means any Holder or beneficial owner of Preferred
Securities.

     "Event of Default" means (a) a failure by the Guarantor to perform any of
its payments or other obligations under this Preferred Securities Guarantee or
(b) if applicable, the failure by the Guarantor to deliver Common Stock upon an
appropriate election by a Holder of Preferred Securities to convert the
Preferred Securities into shares of Common Stock.

     "Guarantee Payments" means the following payments or distributions, without
duplication, with respect to the Preferred Securities, to the extent not paid or
made by the Issuer: (i) any accrued and unpaid Distributions (as defined in the
Declaration) that are required to be paid on such Preferred Securities to the
extent the Issuer shall have funds available therefor, (ii) the redemption price
(the "Redemption Price"), and all accrued and unpaid Distributions to the date
of redemption, to the extent the Issuer has funds available therefor, with
respect to any Preferred Securities called for redemption by the Issuer, and
(iii) upon a voluntary or involuntary dissolution, winding-up or 

                                       2

 
termination of the Issuer (other than in connection with the redemption of all
of the Preferred Securities or the distribution of the Debt Securities to the
Holders in exchange for Preferred Securities as provided in the Declaration),
the lesser of (a) the aggregate of the liquidation amount and all accrued and
unpaid Distributions on the Preferred Securities to the date of payment, to the
extent the Issuer shall have funds available therefor, and (b) the amount of
assets of the Issuer remaining available for distribution to Holders of
Preferred Securities then outstanding upon the liquidation of the Issuer (in
either case, the "Liquidation Distribution"). If an Event of Default (as defined
in the Indenture) has occurred and is continuing, the rights of holders of the
Common Securities to receive payments under the Common Securities Guarantee
Agreement are subordinated to the rights of Holders of Preferred Securities to
receive Guarantee Payments.

     "Holder" shall mean any holder, as registered on the books and records of
the Issuer, of any Preferred Securities; provided, however, that, in determining
whether the holders of the requisite percentage of Preferred Securities have
given any request, notice, consent or waiver hereunder, "Holder" shall not
include the Guarantor or any Affiliate of the Guarantor.

     "Indemnified Person" means the Preferred Guarantee Trustee, any Affiliate
of the Preferred Guarantee Trustee, or any officers, directors, shareholders,
members, partners, employees, representatives, nominees, custodians or agents of
the Preferred Guarantee Trustee.

     "Indenture" means the Indenture dated as of [            ], between the
Guarantor and [             ], as trustee.

     "Majority in liquidation amount of the Preferred Securities" means, except
as provided in the terms of the Preferred Securities, or except as provided by
the Trust Indenture Act, a vote by Holder(s), voting separately as a class, of
more than 50% of the liquidation amount (including the stated amount that would
be paid on redemption, liquidation or otherwise, plus accrued and unpaid
Distributions to the date upon which the voting percentages are determined) of
all Preferred Securities.

     "Person" means any individual, corporation, partnership, limited liability
company, joint venture, association, joint stock company, trust, unincorporated
organization or government or any agency or political subdivision thereof.

     "Preferred Guarantee Trustee" means [              ], until a Successor
Preferred Guarantee Trustee has been appointed and has accepted such appointment
pursuant to the terms of this Preferred Securities Guarantee and thereafter
means each such Successor Preferred Guarantee Trustee.

     "Responsible Officer" means, with respect to the Preferred Guarantee
Trustee, any officer within the Corporate Trust Office of the Preferred
Guarantee Trustee, including any vice president, any assistant vice president,
any assistant secretary, the treasurer, any assistant treasurer or other officer
of the Corporate Trust Office of the Preferred Guarantee Trustee customarily
performing functions similar to those performed by any of the above designated
officers, and also means, with respect to a particular corporate trust matter,
any other officer to whom such matter is referred because of that officer's
knowledge of and familiarity with the particular subject.

                                       3

 
     "Successor Preferred Guarantee Trustee" means a successor Preferred
Guarantee Trustee possessing the qualifications to act as Preferred Guarantee
Trustee under Section 4.1.

     "Trust Securities" means the Common Securities and the Preferred
Securities.


                                   ARTICLE II

                              TRUST INDENTURE ACT

      SECTION 2.1  Trust Indenture Act; Application.

     (a) Upon its public offering pursuant to the registration requirements of
the Securities Act, this Preferred Securities Guarantee will be subject to the
provisions of the Trust Indenture Act that will be required to be part of this
Preferred Securities Guarantee and shall, to the extent applicable, be governed
by such provisions; and

     (b) if and to the extent that any provision of this Preferred Securities
Guarantee limits, qualifies or conflicts with the duties imposed by Sections 310
to 317, inclusive, of the Trust Indenture Act, such imposed duties shall
control.

     SECTION 2.2  Lists of Holders.

     (a) The Guarantor shall provide the Preferred Guarantee Trustee with a
list, in such form as the Preferred Guarantee Trustee may reasonably require, of
the names and addresses of the Holders ("List of Holders") (i) within 14 days
after each record date for payment of Distributions, as of such record date, and
(ii) at any other time, within 30 days of receipt by the Guarantor of a written
request for a List of Holders as of a date no more than 14 days before such List
of Holders is given to the Preferred Guarantee Trustee, provided that the
Guarantor shall not be obligated to provide such List of Holders at any time the
List of Holders does not differ from the most recent List of Holders given to
the Preferred Guarantee Trustee by the Guarantor.  The Preferred Guarantee
Trustee may destroy any List of Holders previously given to it on receipt of a
new List of Holders.

     (b) The Preferred Guarantee Trustee shall comply with its obligations under
Sections 311(a), 311(b) and Section 312(b) of the Trust Indenture Act.

     SECTION 2.3  Reports by the Preferred Guarantee Trustee.

     Within 60 days after May 15 of each year, the Preferred Guarantee Trustee
shall provide to the Holders such reports as are required by Section 313 of the
Trust Indenture Act, if any, in the form and in the manner provided by Section
313 of the Trust Indenture Act.  The Preferred Guarantee Trustee shall also
comply with the requirements of Section 313(d) of the Trust Indenture Act.

                                       4

 
      SECTION 2.4  Periodic Reports to Preferred Guarantee Trustee.

     The Guarantor shall provide to the Preferred Guarantee Trustee such
documents, reports and information (if any) as are required by Section 314 and
the compliance certificate required by Section 314 of the Trust Indenture Act in
the form, the manner and at the times required by Section 314 of the Trust
Indenture Act.

     Delivery of such reports, information and documents to the Preferred
Guarantee Trustee is for informational purposes only and the Preferred Guarantee
Trustee's receipt of such shall not constitute constructive notice of any
information contained therein, including the Guarantor's compliance with any of
its covenants hereunder (as to which the Preferred Guarantee Trustee is entitled
to rely exclusively on Officers' Certificates).

     SECTION 2.5  Evidence of Compliance with Conditions Precedent.

     The Guarantor shall provide to the Preferred Guarantee Trustee such
evidence of compliance with any conditions precedent, if any, provided for in
this Preferred Securities Guarantee that relate to any of the matters set forth
in Section 314(c) of the Trust Indenture Act.  Any certificate or opinion
required to be given by an officer pursuant to Section 314(c)(1) may be given in
the form of an Officers' Certificate.

     SECTION 2.6  Events of Default; Waiver.

     The Holders of a Majority in liquidation amount of Preferred Securities
may, by vote, on behalf of the Holders of all of the Preferred Securities, waive
any past Event of Default and its consequences.  Upon such waiver, any such
Event of Default shall cease to exist, and any Event of Default arising
therefrom shall be deemed to have been cured, for every purpose of this
Preferred Securities Guarantee, but no such waiver shall extend to any
subsequent or other default or Event of Default or impair any right consequent
thereon.

     SECTION 2.7  Event of Default; Notice.

     (a) The Preferred Guarantee Trustee shall, within 90 days after the
occurrence of an Event of Default actually known to a Responsible Officer of the
Preferred Guarantee Trustee, transmit by mail, first class postage prepaid, to
the Holders, notices of all such Events of Default unless such defaults have
been cured before the giving of such notice, provided that the Preferred
Guarantee Trustee shall be protected in withholding such notice if and so long
as a Responsible Officer of the Preferred Guarantee Trustee in good faith
determines that the withholding of such notice is in the interests of the
Holders.

     (b) The Preferred Guarantee Trustee shall not be deemed to have knowledge
of any Event of Default unless the Preferred Guarantee Trustee shall have
received written notice thereof, or a Responsible Officer of the Preferred
Guarantee Trustee charged with the administration of this Preferred Securities
Guarantee shall have obtained actual knowledge thereof.

                                       5

 
     SECTION 2.8  Conflicting Interests.

     The Declaration shall be deemed to be specifically described in this
Preferred Securities Guarantee for the purposes of clause (i) of the first
proviso contained in Section 310(b) of the Trust Indenture Act.


                                  ARTICLE III

           POWERS, DUTIES AND RIGHTS OF PREFERRED GUARANTEE TRUSTEE

     SECTION 3.1  Powers and Duties of the Preferred Guarantee Trustee.

     (a) This Preferred Securities Guarantee shall be held by the Preferred
Guarantee Trustee for the benefit of the Holders and the Preferred Guarantee
Trustee shall not transfer this Preferred Securities Guarantee to any Person
except a Holder exercising his or her rights pursuant to Section 5.4(b) or to a
Successor Preferred Guarantee Trustee on acceptance by such Successor Preferred
Guarantee Trustee of its appointment to act as Successor Preferred Guarantee
Trustee.  The right, title and interest of the Preferred Guarantee Trustee shall
automatically vest in any Successor Preferred Guarantee Trustee, and such
vesting and succession of title shall be effective whether or not conveyancing
documents have been executed and delivered pursuant to the appointment of such
Successor Preferred Guarantee Trustee.

     (b) If an Event of Default actually known to a Responsible Officer of the
Preferred Guarantee Trustee has occurred and is continuing, the Preferred
Guarantee Trustee shall enforce this Preferred Securities Guarantee for the
benefit of the Holders.

     (c) The Preferred Guarantee Trustee, before the occurrence of any Event of
Default and after the curing of all Events of Default that may have occurred,
shall undertake to perform only such duties as are specifically set forth in
this Preferred Securities Guarantee, and no implied covenants shall be read into
this Preferred Securities Guarantee against the Preferred Guarantee Trustee.  In
case an Event of Default has occurred (that has not been cured or waived
pursuant to Section 2.6) and is actually known to a Responsible Officer of the
Preferred Guarantee Trustee, the Preferred Guarantee Trustee shall exercise such
of the rights and powers vested in it by this Preferred Securities Guarantee,
and shall use the same degree of care and skill in its exercise thereof as a
prudent person would exercise or use under the circumstances in the conduct of
his or her own affairs.

     (d)  No provision of this Preferred Securities Guarantee shall be construed
to relieve the Preferred Guarantee Trustee from liability for its own negligent
action, its own negligent failure to act, or its own willful misconduct, except
that:

          (i)  prior to the occurrence of any Event of Default and after the
     curing or waiving of all such Events of Default that may have occurred:

               (A) the duties and obligations of the Preferred Guarantee Trustee
          shall be determined solely by the express provisions of this Preferred
          Securities Guarantee, 

                                       6

 
          and the Preferred Guarantee Trustee shall not be liable except for the
          performance of such duties and obligations as are specifically set
          forth in this Preferred Securities Guarantee, and no implied covenants
          or obligations shall be read into this Preferred Securities Guarantee
          against the Preferred Guarantee Trustee; and

               (B) in the absence of bad faith on the part of the Preferred
          Guarantee Trustee, the Preferred Guarantee Trustee may conclusively
          rely, as to the truth of the statements and the correctness of the
          opinions expressed therein, upon any certificates or opinions
          furnished to the Preferred Guarantee Trustee and conforming to the
          requirements of this Preferred Securities Guarantee; but in the case
          of any such certificates or opinions that by any provision hereof are
          specifically required to be furnished to the Preferred Guarantee
          Trustee, the Preferred Guarantee Trustee shall be under a duty to
          examine the same to determine whether or not they conform to the
          requirements of this Preferred Securities Guarantee;

          (ii)  the Preferred Guarantee Trustee shall not be liable for any
     error of judgment made in good faith by a Responsible Officer of the
     Preferred Guarantee Trustee, unless it shall be proved that the Preferred
     Guarantee Trustee was negligent in ascertaining the pertinent facts upon
     which such judgment was made;

          (iii) the Preferred Guarantee Trustee shall not be liable with respect
     to any action taken or omitted to be taken by it in good faith in
     accordance with the direction of the Holders of not less than a Majority in
     liquidation amount of the Preferred Securities relating to the time, method
     and place of conducting any proceeding for any remedy available to the
     Preferred Guarantee Trustee, or exercising any trust or power conferred
     upon the Preferred Guarantee Trustee under this Preferred Securities
     Guarantee; and

          (iv)  no provision of this Preferred Securities Guarantee shall
     require the Preferred Guarantee Trustee to expend or risk its own funds or
     otherwise incur personal financial liability in the performance of any of
     its duties or in the exercise of any of its rights or powers, if the
     Preferred Guarantee Trustee shall have reasonable grounds for believing
     that the repayment of such funds or liability is not reasonably assured to
     it under the terms of this Preferred Securities Guarantee or indemnity,
     reasonably satisfactory to the Preferred Guarantee Trustee, against such
     risk or liability is not reasonably assured to it.

     SECTION 3.2  Certain Rights of Preferred Guarantee Trustee.

     (a) Subject to the provisions of Section 3.1:

         (i)  The Preferred Guarantee Trustee may conclusively rely, and shall
     be fully protected in acting or refraining from acting upon, any
     resolution, certificate, statement, instrument, opinion, report, notice,
     request, direction, consent, order, bond, debenture, note, other evidence
     of indebtedness or other paper or document believed by it to be genuine and
     to have been signed, sent or presented by the proper party or parties.

                                       7

 
          (ii)   Any direction or act of the Guarantor contemplated by this
     Preferred Securities Guarantee shall be sufficiently evidenced by an
     Officers' Certificate.

          (iii)  Whenever, in the administration of this Preferred Securities
     Guarantee, the Preferred Guarantee Trustee shall deem it desirable that a
     matter be proved or established before taking, suffering or omitting any
     action hereunder, the Preferred Guarantee Trustee (unless other evidence is
     herein specifically prescribed) may, in the absence of bad faith on its
     part, request and conclusively rely upon an Officers' Certificate which,
     upon receipt of such request, shall be promptly delivered by the Guarantor.

          (iv)   The Preferred Guarantee Trustee shall have no duty to see to
     any recording, filing or registration of any instrument (or any
     rerecording, refiling or re-registration thereof).

          (v)    The Preferred Guarantee Trustee may consult with counsel of its
     selection, and the advice or opinion of such counsel with respect to legal
     matters shall be full and complete authorization and protection in respect
     of any action taken, suffered or omitted by it hereunder in good faith and
     in accordance with such advice or opinion.  Such counsel may be counsel to
     the Guarantor or any of its Affiliates and may include any of its
     employees.  The Preferred Guarantee Trustee shall have the right at any
     time to seek instructions concerning the administration of this Preferred
     Securities Guarantee from any court of competent jurisdiction.

          (vi)   The Preferred Guarantee Trustee shall be under no obligation to
     exercise any of the rights or powers vested in it by this Preferred
     Securities Guarantee at the request or direction of any Holder, unless such
     Holder shall have provided to the Preferred Guarantee Trustee such security
     and indemnity, reasonably satisfactory to the Preferred Guarantee Trustee,
     against the costs, expenses (including attorneys' fees and expenses and the
     expenses of the Preferred Guarantee Trustee's agents, nominees or
     custodians) and liabilities that might be incurred by it in complying with
     such request or direction, including such reasonable advances as may be
     requested by the Preferred Guarantee Trustee; provided that nothing
     contained in this Section 3.2(a)(vi) shall be taken to relieve the
     Preferred Guarantee Trustee, upon the occurrence of an Event of Default, of
     its obligation to exercise the rights and powers vested in it by this
     Preferred Securities Guarantee.

          (vii)  The Preferred Guarantee Trustee shall not be bound to make any
     investigation into the facts or matters stated in any resolution,
     certificate, statement, instrument, opinion, report, notice, request,
     direction, consent, order, bond, debenture, note, other evidence of
     indebtedness or other paper or document, but the Preferred Guarantee
     Trustee, in its discretion, may make such further inquiry or investigation
     into such facts or matters as it may see fit.

          (viii) The Preferred Guarantee Trustee may execute any of the trusts
     or powers hereunder or perform any duties hereunder either directly or by
     or through agents, nominees, custodians or attorneys, and the Preferred
     Guarantee Trustee shall not be responsible for any misconduct or negligence
     on the part of any agent or attorney appointed with due care by it
     hereunder.

                                       8

 
          (ix)  Any action taken by the Preferred Guarantee Trustee or its
     agents hereunder shall bind the Holders and the signature of the Preferred
     Guarantee Trustee or its agents alone shall be sufficient and effective to
     perform any such action. No third party shall be required to inquire as to
     the authority of the Preferred Guarantee Trustee to so act or as to its
     compliance with any of the terms and provisions of this Preferred
     Securities Guarantee, both of which shall be conclusively evidenced by the
     Preferred Guarantee Trustee's or its agent's taking such action.

          (x)   Whenever in the administration of this Preferred Securities
     Guarantee the Preferred Guarantee Trustee shall deem it desirable to
     receive instructions with respect to enforcing any remedy or right or
     taking any other action hereunder, the Preferred Guarantee Trustee (i) may
     request instructions from the Holders of a Majority in liquidation amount
     of the Preferred Securities, (ii) may refrain from enforcing such remedy or
     right or taking such other action until such instructions are received, and
     (iii) shall be protected in conclusively relying on or acting in accordance
     with such instructions.

          (xi)  The Preferred Securities Trustee shall not be liable for any
     action taken, suffered, or omitted to be taken by it in good faith and
     reasonably believed by it to be authorized or within the discretion or
     rights or powers conferred upon it by this Preferred Securities Guarantee.

     (b)  No provision of this Preferred Securities Guarantee shall be deemed to
impose any duty or obligation on the Preferred Guarantee Trustee to perform any
act or acts or exercise any right, power, duty or obligation conferred or
imposed on it in any jurisdiction in which it shall be illegal, or in which the
Preferred Guarantee Trustee shall be unqualified or incompetent in accordance
with applicable law, to perform any such act or acts or to exercise any such
right, power, duty or obligation.  No permissive power or authority available to
the Preferred Guarantee Trustee shall be construed to be a duty.

     SECTION 3.3  Not Responsible for Recitals or Issuance of Preferred
Securities Guarantee.

     The recitals contained in this Preferred Securities Guarantee shall be
taken as the statements of the Guarantor, and the Preferred Guarantee Trustee
does not assume any responsibility for their correctness.  The Preferred
Guarantee Trustee makes no representation as to the validity or sufficiency of
this Preferred Securities Guarantee.

                                       9

 
                                   ARTICLE IV

                          PREFERRED GUARANTEE TRUSTEE

     SECTION 4.1  Preferred Guarantee Trustee: Eligibility.

     (a) There shall at all times be a Preferred Guarantee Trustee which shall:

         (i)   not be an Affiliate of the Guarantor; and

         (ii)  be a corporation organized and doing business under the laws of
     the United States of America or any State or Territory thereof or of the
     District of Columbia, or a corporation or Person permitted by the
     Securities and Exchange Commission to act as an institutional trustee under
     the Trust Indenture Act, authorized under such laws to exercise corporate
     trust powers, having a combined capital and surplus of at least 50 million
     U.S. dollars ($50,000,000), and subject to supervision or examination by
     federal, state, territorial or District of Columbia authority.  If such
     corporation publishes reports of condition at least annually, pursuant to
     law or to the requirements of the supervising or examining authority
     referred to above, then, for the purposes of this Section 4.1(a)(ii), the
     combined capital and surplus of such corporation shall be deemed to be its
     combined capital and surplus as set forth in its most recent report of
     condition so published.

     (b) If at any time the Preferred Guarantee Trustee shall cease to be
eligible to so act under Section 4.1(a), the Preferred Guarantee Trustee shall
immediately resign in the manner and with the effect set out in Section 4.2(c).

     (c) If the Preferred Guarantee Trustee has or shall acquire any
"conflicting interest" within the meaning of Section 310(b) of the Trust
Indenture Act, the Preferred Guarantee Trustee and Guarantor shall in all
respects comply with the provisions of Section 310(b) of the Trust Indenture
Act.

     SECTION 4.2  Appointment, Removal and Resignation of Preferred Guarantee
Trustee.

     (a) Subject to Section 4.2(b), the Preferred Guarantee Trustee may be
appointed or removed without cause at any time by the Guarantor.

     (b) The Preferred Guarantee Trustee shall not be removed in accordance with
Section 4.2(a) until a Successor Preferred Guarantee Trustee has been appointed
and has accepted such appointment by written instrument executed by such
Successor Preferred Guarantee Trustee and delivered to the Guarantor.

     (c) The Preferred Guarantee Trustee appointed to office shall hold office
until a Successor Preferred Guarantee Trustee shall have been appointed or until
its removal or resignation.  The Preferred Guarantee Trustee may resign from
office (without need for prior or subsequent accounting) by an instrument in
writing executed by the Preferred Guarantee Trustee and delivered to the
Guarantor, which resignation shall not take effect until a Successor Preferred
Guarantee 

                                       10

 
Trustee has been appointed and has accepted such appointment by instrument in
writing executed by such Successor Preferred Guarantee Trustee and delivered to
the Guarantor and the resigning Preferred Guarantee Trustee.

     (d) If no Successor Preferred Guarantee Trustee shall have been appointed
and accepted appointment as provided in this Section 4.2 within 60 days after
delivery of an instrument of resignation or removal, the Preferred Guarantee
Trustee resigning or being removed may petition any court of competent
jurisdiction for appointment of a Successor Preferred Guarantee Trustee.  Such
court may thereupon, after prescribing such notice, if any, as it may deem
proper, appoint a Successor Preferred Guarantee Trustee.

     (e) No Preferred Guarantee Trustee shall be liable for the acts or
omissions to act of any Successor Preferred Guarantee Trustee.

     (f) Upon termination of this Preferred Securities Guarantee or removal or
resignation of the Preferred Guarantee Trustee pursuant to this Section 4.2, the
Guarantor shall pay to the Preferred Guarantee Trustee all amounts accrued to
the date of such termination, removal or resignation.


                                   ARTICLE V

                                   GUARANTEE

     SECTION 5.1  Guarantee.

     The Guarantor irrevocably and unconditionally agrees to pay in full to the
Holders the Guarantee Payments (without duplication of amounts theretofore paid
by the Issuer), as and when due, regardless of any defense, right of set-off or
counterclaim that the Issuer may have or assert. The Guarantor's obligation to
make a Guarantee Payment may be satisfied by direct payment of the required
amounts by the Guarantor to the Holders or by causing the Issuer to pay such
amounts to the Holders.  The Guarantor will honor all obligations, if any,
relating to the conversion of the Preferred Securities into the Common Stock of
the Guarantor as set forth in the Declaration and the Indenture.

     SECTION 5.2  Waiver of Notice and Demand.

     The Guarantor hereby waives notice of acceptance of this Preferred
Securities Guarantee and of any liability to which it applies or may apply,
presentment, demand for payment, any right or remedy to require a proceeding
first against the Issuer or any other Person before proceeding directly against
the Guarantor, protest, notice of nonpayment, notice of dishonor, notice of
redemption and all other notices and demands.

    SECTION 5.3  Obligations Not Affected.

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     The obligations, covenants, agreements and duties of the Guarantor under
this Preferred Securities Guarantee shall in no way be affected or impaired by
reason of the happening from time to time of any of the following:

     (a) the release or waiver, by operation of law or otherwise, of the
performance or observance by the Issuer of any express or implied agreement,
covenant, term or condition relating to the Preferred Securities to be performed
or observed by the Issuer;

     (b) the extension of time for the payment by the Issuer of all or any
portion of the Distributions, Redemption Price, Liquidation Distribution or any
other sums payable under the terms of the Preferred Securities or the extension
of time for the performance of any other obligation under, arising out of, or in
connection with, the Preferred Securities (other than an extension of time for
payment of Distributions, Redemption Price, Liquidation Distribution or other
sum payable that results from the extension of any interest payment period on
the Debt Securities;

     (c) any failure, omission, delay or lack of diligence on the part of the
Holders to enforce, assert or exercise any right, privilege, power or remedy
conferred on the Holders pursuant to the terms of the Preferred Securities, or
any action on the part of the Issuer granting indulgence or extension of any
kind;

     (d) the voluntary or involuntary liquidation, dissolution, sale of any
collateral, receiver ship, insolvency, bankruptcy, assignment for the benefit of
creditors, reorganization, arrangement, composition or readjustment of debt of,
or other similar proceedings affecting, the Issuer or any of the assets of the
Issuer;

     (e) any invalidity of, or defect or deficiency in, the Preferred
Securities;

     (f) the settlement or compromise of any obligation guaranteed hereby or
hereby incurred; or

     (g) any other circumstance whatsoever that might otherwise constitute a
legal or equitable discharge or defense of a guarantor, it being the intent of
this Section 5.3 that the obligations of the Guarantor hereunder shall be
absolute and unconditional under any and all circumstances.

     There shall be no obligation of the Holders to give notice to, or obtain
consent of, the Guarantor with respect to the happening of any of the foregoing.

     SECTION 5.4  Rights of Holders.

     (a) The Holders of a Majority in liquidation amount of the Preferred
Securities then outstanding have the right to direct the time, method and place
of conducting any proceeding for any remedy available to the Preferred Guarantee
Trustee in respect of this Preferred Securities Guarantee or to direct the
exercise of any trust or power conferred upon the Preferred Guarantee Trustee
under this Preferred Securities Guarantee.

                                       12

 
     (b) If the Preferred Guarantee Trustee fails to enforce this Preferred
Securities Guarantee, any Holder of Preferred Securities may institute a legal
proceeding directly against the Guarantor to enforce the Preferred Guarantee
Trustee's rights under this Preferred Securities Guarantee, without first
instituting a legal proceeding against the Issuer, the Preferred Guarantee
Trustee or any other person or entity.  The Guarantor waives any right or remedy
to require that any action be brought first against the Issuer or any other
person or entity before proceeding directly against the Guarantor.
Notwithstanding the foregoing, if the Guarantor has failed to make a guarantee
payment, a Holder of Preferred Securities may directly institute a proceeding
against the Guarantor for enforcement of this Preferred Securities Guarantee for
such payment.

     SECTION 5.5  Guarantee of Payment.

     This Preferred Securities Guarantee creates a guarantee of payment and not
of collection.

     SECTION 5.6  Subrogation.

     The Guarantor shall be subrogated to all (if any) rights of the Holders of
Preferred Securities against the Issuer in respect of any amounts paid to such
Holders by the Guarantor under this Preferred Securities Guarantee; provided,
however, that the Guarantor shall not (except to the extent required by
mandatory provisions of law) be entitled to enforce or exercise any right that
it may acquire by way of subrogation or any indemnity, reimbursement or other
agreement, in all cases as a result of payment under this Preferred Securities
Guarantee, if, at the time of any such payment, any amounts are due and unpaid
under this Preferred Securities Guarantee.  If any amount shall be paid to the
Guarantor in violation of the preceding sentence, the Guarantor agrees to hold
such amount in trust for the Holders and to pay over such amount to the Holders.

     SECTION 5.7  Independent Obligations.

     The Guarantor acknowledges that its obligations hereunder are independent
of the obligations of the Issuer with respect to the Preferred Securities, and
that the Guarantor shall be liable as principal and as debtor hereunder to make
Guarantee Payments pursuant to the terms of this Preferred Securities Guarantee
notwithstanding the occurrence of any event referred to in subsections (a)
through (g), inclusive, of Section 5.3 hereof.


                                   ARTICLE VI

                   LIMITATION OF TRANSACTIONS; SUBORDINATION

     SECTION 6.1  Limitation of Transactions.

     So long as any Preferred Securities remain outstanding, if (i) the
Guarantor has exercised its option to defer interest payments on the Debt
Securities by extending the interest payment period and such extension period,
or any extension thereof, shall be continuing, (ii) the Guarantor shall be in
default with respect to its payment or other obligations under this Preferred
Securities Guarantee or (iii) there shall have occurred and be continuing an
Event of Default under the Declaration or any 

                                       13

 
event that, with the giving of notice or lapse of time or both, would constitute
an Event of Default under the Declaration, then the Guarantor shall not (a)
declare or pay any dividend on, make any distributions with respect to, or
redeem, purchase, acquire, or make any liquidation payment with respect to, any
of its capital stock or (b) make any payment of interest, principal or premium,
if any, on or repay, repurchase or redeem any debt securities of the Guarantor
that rank pari passu with or junior in interest to the Debt Securities or make
any guarantee payment with respect to any guarantee by the Guarantor of the debt
securities of any subsidiary of the Guarantor if such guarantee ranks pari passu
with or junior in interest to the Debt Securities (other than (i) as a result of
a reclassification of the capital stock of the Guarantor or the exchange or
conversion of one class or series of the capital stock of the Guarantor for
another class or series of the capital stock of the Guarantor, (ii) the purchase
of fractional interests in shares of the capital stock of the Guarantor pursuant
to the conversion or exchange provisions of such capital stock or the security
being converted into or exchanged for such capital stock, (iii) dividends or
distributions in Common Stock of the Guarantor, (iv) any declaration of a
dividend in connection with the implementation of a stockholders' rights plan,
or the issuance of stock under any such plan in the future, or the redemption or
repurchase of any such rights pursuant thereto, (v) payments under the Guarantee
and Common Securities Guarantee, (vi) purchases of Common Stock of the Guarantor
related to the issuance of Common Stock of the Guarantor or rights under any of
the Guarantor's benefit plans for its directors, officers or employees and (vii)
obligations under any dividend reinvestment and stock purchase plans).

     SECTION 6.2  Subordination.

     This Preferred Securities Guarantee will constitute an unsecured obligation
of the Guarantor and will rank (i) subordinate and junior in right of payment to
all other liabilities of the Guarantor (except any liabilities that may be pari
passu expressly by their terms), (ii) pari passu with the most senior preferred
or preference stock now or hereafter issued by the Guarantor and with any
guaranty now or hereafter entered into by the Guarantor in respect of any
preferred or preference stock of any Affiliate of the Guarantor and (iii) senior
to the Guarantor's common stock.


                                  ARTICLE VII

                                  TERMINATION

     SECTION 7.1  Termination.

     This Preferred Securities Guarantee shall terminate as to each Holder upon
(i) full payment of the Redemption Price and accrued and unpaid distributions
with respect to all Preferred Securities, (ii) the distribution of the Common
Stock to such Holder upon the conversion of such Holder's Preferred Securities
into the Common Stock, (iii) the distribution of the Debt Securities to the
Holders of the Preferred Securities or (iv) full payment of the amounts payable
in accordance with the Declaration upon liquidation of the Issuer.  This
Preferred Securities Guarantee shall terminate completely upon full payment of
the amounts payable in accordance with the Declaration. Notwithstanding the
foregoing, this Preferred Securities Guarantee will continue to be effective or
will be reinstated, as the case may be, if at any time any Holder must restore
payment of any sum paid under the Preferred Securities or under this Preferred
Securities Guarantee.

                                       14

 
                                  ARTICLE VII

                                INDEMNIFICATION

     SECTION 8.1  Exculpation.

     (a) No Indemnified Person shall be liable, responsible or accountable in
damages or otherwise to the Guarantor or any Covered Person for any loss,
damage, liability, expense or claim incurred by reason of any act or omission
performed or omitted by such Indemnified Person in good faith in accordance with
this Preferred Securities Guarantee and in a manner that such Indemnified Person
reasonably believed to be within the scope of the authority conferred on such
Indemnified Person by this Preferred Securities Guarantee or by law, except that
an Indemnified Person shall be liable for any such loss, damage or claim
incurred by reason of such Indemnified Person's negligence or willful misconduct
with respect to such acts or omissions.

     (b) An Indemnified Person shall be fully protected in relying in good faith
upon the records of the Guarantor and upon such information, opinions, reports
or statements presented to the Guarantor by any Person as to matters the
Indemnified Person reasonably believes are within such other Person's
professional or expert competence and who has been selected with reasonable care
by or on behalf of the Guarantor, including information, opinions, reports or
statements as to the value and amount of the assets, liabilities, profits,
losses or any other facts pertinent to the existence and amount of assets from
which Distributions to Holders might properly be paid.

     SECTION 8.2  Indemnification.

     The Guarantor agrees to indemnify each Indemnified Person for, and to hold
each Indemnified Person harmless against, any loss, liability or expense
incurred without negligence or bad faith on its part, arising out of or in
connection with the acceptance or administration of the trust or trusts
hereunder, including the costs and expenses (including reasonable legal fees and
expenses) of defending itself against, or investigating, any claim or liability
in connection with the exercise or performance of any of its powers or duties
hereunder.  The provisions of this Section 8.2 shall survive the termination of
this Preferred Securities Guarantee or the resignation or removal of the
Preferred Guarantee Trustee.

     When the Preferred Guarantee Trustee incurs expenses or renders services in
connection with an Event of Default specified in Section 5.1(d) or Section
5.1(e) of the Indenture, the expenses (including the reasonable charges and
expenses of its counsel) and the compensation for services are intended to
constitute expenses of administration under any applicable federal or state
bankruptcy, insolvency or other similar law.

                                       15

 
                                   ARTICLE IX

                                 MISCELLANEOUS

     SECTION 9.1  Successors and Assigns.

     All guarantees and agreements contained in this Preferred Securities
Guarantee shall bind the successors, assigns, receivers, trustees and
representatives of the Guarantor and shall inure to the benefit of the Holders
of the Preferred Securities then outstanding.  Except in connection with any
merger or consolidation of the Guarantor with or into another entity permitted
by Section 9.1 of the Indenture or any sale, transfer or lease of the
Guarantor's assets to another entity permitted by Section 9.1 of the Indenture,
the Guarantor may not assign its rights or delegate its obligations under this
Preferred Securities Guarantee without the prior approval of the holders of at
least a Majority in liquidation amount of the Preferred Securities then
outstanding.

     SECTION 9.2  Amendments.

     Except with respect to any changes that do not adversely affect the rights
of Holders (in which case no consent of Holders will be required), this
Preferred Securities Guarantee may only be amended with the prior approval of
the Holders of at least a Majority in liquidation amount (including the stated
amount that would be paid on redemption, liquidation or otherwise, plus accrued
and unpaid Distributions to the date upon which the voting percentages are
determined) of the Preferred Securities then outstanding. The provisions of the
Declaration with respect to meetings of Holders apply to the giving of such
approval.

     SECTION 9.3  Notices.

     All notices provided for in this Preferred Securities Guarantee shall be in
writing, duly signed by the party giving such notice, and shall be delivered,
telecopied or mailed by first class mail, as follows:

     (a) If given to the Preferred Guarantee Trustee, at the Preferred Guarantee
Trustee's mailing address set forth below (or such other address as the
Preferred Guarantee Trustee may give notice of to the Holders of the Preferred
Securities):



               Attention:  [     ]

                                       16

 
     (b) If given to the Guarantor, at the Guarantor's mailing address set forth
below (or such other address as the Guarantor may give notice of to the Holders
of the Preferred Securities):

               McKesson Corporation
               McKesson Plaza
               One Post Street
               San Francisco, California  94104

               Attention:  General Counsel

     (c) If given to any Holder of Preferred Securities, at the address set
forth on the books and records of the Issuer.

     All such notices shall be deemed to have been given when received in
person, telecopied with receipt confirmed, or mailed by first class mail,
postage prepaid, except that if a notice or other document is refused delivery
or cannot be delivered because of a changed address of which no notice was
given, such notice or other document shall be deemed to have been delivered on
the date of such refusal or inability to deliver.

     SECTION 9.4  Benefit.

     This Preferred Securities Guarantee is solely for the benefit of the
Holders of the Preferred Securities and, subject to Section 3.1(a), is not
separately transferable from the Preferred Securities.

     SECTION 9.5  Governing Law.

     THIS PREFERRED SECURITIES GUARANTEE SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK AS APPLIED TO CONTRACTS MADE
AND PERFORMED WITHIN THE STATE OF NEW YORK INCLUDING, WITHOUT LIMITATION,
SECTION 5-1401 OF THE NEW YORK GENERAL OBLIGATIONS LAW.

                                     

                                       17

 
     THIS PREFERRED SECURITIES GUARANTEE is executed as of the day and year
first above written.


                                      McKESSON CORPORATION, as Guarantor


 
                                      By: ______________________________________
                                          Name:
                                          Title:


                                      [        ], as Preferred Guarantee Trustee

 
                                      By: ______________________________________
                                          Name:
                                          Title:

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