698117_3.DOC
                                3
                            AGREEMENT

     This  Agreement is entered into effective as of May 4,  2006
between  Southwest Royalties, Inc., a Delaware  corporation  (the
"Company")  and  Southwest Oil & Gas Income  Fund  X-B,  L.P.,  a
Delaware partnership (the "Partnership").

                            Recitals

     The   Company  is  the  managing  general  partner  of   the
Partnership.

     The  Company currently owns or holds and may in  the  future
acquire, own or hold limited partnership interests or units as  a
limited   partner  of  the  Partnership  (the  "Limited   Partner
Interests").

     The  Company and the Partnership desire to resolve or  avoid
any  uncertainties regarding the relative voting  rights  of  the
Company,  as  a  holder  of Limited Partner  Interests,  and  the
Unaffiliated Holders.

     The  Company  and  the  Partnership desire  to  confer  upon
holders  of  limited  partnership  interests  or  units  in   the
Partnership who are Unaffiliated Holders (as defined below)  have
voting rights to remove a general partner of the Partnership that
are   consistent  with  the  Administrative  Guidelines  for  the
Registration  of  Oil and Gas Programs set forth  in  subsections
(f)(1)(C) and (f)(2) of Section 121.8 of the Regulations  of  the
State Securities Board of Texas.

     Accordingly, in consideration of the premises and for  other
good  and valuable consideration, the receipt and sufficiency  of
which  are  hereby acknowledged, the Company and the  Partnership
agree as follows:

1.    Applicability. This Agreement shall apply to the voting  of
all Limited Partner Interests in the Partnership now or hereafter
owned or held by the Company or any affiliate of the Company,  as
defined  in Rule 405 under the Securities Act of 1933, as amended
("Affiliate"), on any matter submitted to a vote of  the  holders
of  limited  partnership interests or units  in  the  Partnership
regarding  the removal of the Company as general partner  of  the
Partnership.  This Agreement shall not apply to the voting of (i)
any  Limited Partner Interest on any other matter submitted to  a
vote of the holders of limited partnership interests or units  in
the  Partnership or (ii) any interest now or hereafter  owned  or
held by the Company or any Affiliate as a general partner of  the
Partnership on any matter submitted to a vote of the partners  or
holders  of  limited  partnership  interests  or  units  in   the
Partnership.

2.   Voting Limited Partner Interests on Certain Matters.

     (a)   Except  as  and  to the extent expressly  provided  in
Section  2(b) of this Agreement, the Company shall  not  vote  or
cause  or  permit any person to vote any Limited Partner Interest
on  any  matter regarding the removal of the Company  as  general
partner of the Partnership.

     (b)   If  (i)  the law of the state of organization  or  the
governing  agreement of the Partnership requires or  permits  the
Limited  Partner  Interests  to be included  in  determining  the
requisite  percentage in interest of holders of  limited  partner
interests  or  units in the Partnership necessary  to  approve  a
matter on which the Limited Partner Interests held by the Company
may  not  otherwise  be voted pursuant to Section  2(a)  of  this
Agreement  (the "Requisite Percentage") and (ii) the  holders  of
limited partner interests or units in the Partnership, other than
the  Company  and  its  Affiliates (the "Unaffiliated  Holders"),
voting for or in favor of the removal of a general partner of the
Partnership,  (x)  do not hold the Requisite Percentage  and  (y)
would  hold  the  Requisite Percentage  if  the  Limited  Partner
Interests   were  not  included  in  determining  the   Requisite
Percentage,  the Company shall vote or cause the Limited  Partner
Interests  to  be  voted for or in favor of the removal  of  such
general partner of the Partnership.

     (c)   At any meeting at which holders of limited partnership
interests or units in the Partnership are entitled to vote  on  a
matter  on which the Limited Partner Interests may not  be  voted
pursuant  to  Section  2(a)  of  this  Agreement,  an  authorized
representative of the Company shall attend in person or by  proxy
to  represent the Limited Partner Interests in order to assist in
establishing  a quorum at the meeting, and, except  as  otherwise
required by Section 2(b) of this Agreement, the Partnership shall
cause the minutes of the meeting to record the Company as present
but  not  voting the Limited Partner Interests on any  matter  on
which the Limited Partner Interests may not be voted pursuant  to
Section 2(a) of this Agreement.

     (d)   This  Agreement  shall apply to any  action  taken  by
written  consent of the holders of limited partner  interests  or
units  in  the Partnership in the same manner and with  the  same
effect as if such action were taken or proposed to be taken at  a
meeting  by  the vote of holders of limited partner interests  or
units in the Partnership.

     (e)   During  the term of this Agreement, the Company  shall
not  grant a proxy or power of attorney or enter into any  voting
agreement,   voting  trust  or  other  agreement  or  arrangement
granting  any  person  the  right or authority  to  vote  Limited
Partner  Interests or obligating the Company or any Affiliate  of
the Company to vote Limited Partner Interests in a manner that is
inconsistent with the provisions of this Agreement.

     (f)   During  the term of this Agreement, the Company  shall
not  transfer  or  assign  any Limited Partner  Interest  to  any
Affiliate  of  the  Company unless such  transferee  or  assignee
acknowledges and agrees in writing to be bound by and subject  to
the  terms and conditions of this Agreement.  In order to  insure
compliance with the restrictions referred to herein, the  Company
agrees that the Partnership may issue appropriate "stop transfer"
instructions on the Limited Partner Interests.

     (g)   During the term of this Agreement, the Company and the
Partnership  will  cause  each certificate  or  other  instrument
evidencing any Limited Partner Interest to bear a legend  to  the
following effect:

     "THE   LIMITED   PARTNER  INTERESTS  REPRESENTED   BY   THIS
     CERTIFICATE  ARE  SUBJECT TO RESTRICTIONS  ON  TRANSFER  AND
     RESTRICTIONS ON VOTING AS SET FORTH IN AN AGREEMENT  BETWEEN
     THE  HOLDER OF THESE INTERESTS AND THE PARTNERSHIP.  A  COPY
     OF SUCH AGREEMENT IS ON FILE AT THE PRINCIPAL OFFICES OF THE
     PARTNERSHIP."

3.    Term.  This Agreement shall be in effect as to any  Limited
Partner  Interest during the period commencing on the  date  this
Agreement is executed by the Company and ending on the earlier of
(i) the termination of this Agreement in the manner set forth  in
Section  4  of  this Agreement and (ii) the date upon  which  the
Company and its Affiliates cease to own or hold any interest as a
limited partner of the Partnership.

4.   Termination; Amendment, Modification and Waiver.  Subject to
the  rights,  if  any,  of  the holders  of  limited  partnership
interests  or units in the Partnership to terminate a transaction
or  agreement  between a general partner and the  Partnership  in
accordance with the Partnership Agreement, this Agreement may  be
terminated  and any provision of this Agreement may be  modified,
amended  or waived as to any Limited Partner Interest  only  with
the approval of the Company, the Partnership and the holders of a
majority in interest of the limited partner interests or units of
the Partnership held by Unaffiliated Holders.

5.   Parties in Interest.  The Company and the Partnership intend
to  confer a benefit on the Unaffiliated Holders by granting them
the right, enforceable against the Company, to vote to remove the
Company  as  general  partner  of  the  Partnership  without  the
necessity of the concurrence of the Company.  The Company and the
Partnership  also intend that this benefit cannot be  altered  or
revoked  without  the approval of a majority in interest  of  the
Unaffiliated Holders as provided in Section 4 of this  Agreement.
The Company and the Partnership are entering into this Agreement,
in material part, for the purpose of conferring these benefits on
the  Unaffiliated  Holders.  Accordingly,  the  Company  and  the
Partnership agree that the Unaffiliated Holders shall be entitled
to  enforce the provisions of this Agreement at law or in  equity
as third party beneficiaries of this Agreement.

6.    Governing  Law;  Severability.   This  Agreement  shall  be
governed  in  all  respects by the laws of the  State  of  Texas,
without  regard  to the conflict of laws rules of  the  State  of
Texas.  Wherever possible, each provision of this Agreement shall
be  interpreted in such manner as to be effective and valid under
applicable law, but if any provision of this Agreement becomes or
is  declared by a court of competent jurisdiction to be  invalid,
unenforceable or void under such law, portions of such provision,
or such provision in its entirety, to the extent necessary, shall
be severed from this Agreement without invalidating the remainder
of such provision or the remaining provisions of this Agreement.



                    [Signature pages follow.]

      IN  WITNESS  WHEREOF, the Company and the Partnership  have
caused  this  Agreement to be executed on  the  dates  set  forth
below, to be effective as of May 4, 2006.

                              COMPANY:

                              SOUTHWEST ROYALTIES, INC.



                              By: /s/ L. Paul Latham
                              Name: L. Paul Latham
                              Title:   President

                              Dated: May 4, 2006



                              PARTNERSHIP:

                               Southwest Oil & Gas Income Fund X-
B, L.P.

                              By:    Southwest Royalties, Inc.,
                                     its Managing General Partner



                              By: /s/ Mel G. Riggs
                              Name: Mel G. Riggs
                              Title:   Vice-President

                              Dated: May 4, 2006