STOCK OPTION AGREEMENT dated as of February
                        4, 1995, among NATIONAL AUSTRALIA BANK LIMITED
                        A.C.N. 004044937, an Australian corporation
                        ("Grantee"), MNC ACQUISITION CO., a Michigan
                        corporation and a wholly owned subsidiary of
                        Grantee ("Sub"), and MICHIGAN NATIONAL CORPO-
                        RATION, a Michigan corporation ("Issuer").


                   WHEREAS Issuer is a registered bank holding company
         under the Bank Holding Company Act of 1956, as amended (the
         "BHC Act");

                   WHEREAS Grantee is a commercial bank under Australian
         law and is a foreign bank within the meaning of the Interna-
         tional Banking Act of 1978, as amended;

                   WHEREAS Grantee, Sub and Issuer propose to enter into
         an Agreement and Plan of Merger dated as of the date hereof
         (the "Merger Agreement");

                   WHEREAS, as a condition and inducement to Grantee's
         and Sub's willingness to enter into the Merger Agreement,
         Grantee and Sub have required that Issuer grant to Grantee the
         Option (as defined in Section 2); and

                   WHEREAS the Board of Directors of Issuer, believing
         it to be in the best interests of Issuer, has approved this
         Agreement and the grant by Issuer of the Option.

                   NOW THEREFORE, in consideration of the foregoing and
         the respective representations, warranties, covenants and
         agreements set forth herein and in the Merger Agreement, the
         parties hereto agree as follows:

                   1.  Definitions; Interpretation.  Capitalized terms
         used but not defined herein shall have the meanings set forth
         in the Merger Agreement, which also contains in Section 8.03(b)
         thereof certain rules of construction and interpretation that
         shall be applicable hereto as if set forth herein.

                   2.  Grant of Option.  Issuer hereby grants to Grantee
         an unconditional, irrevocable option (the "Option") to pur-
         chase, subject to the terms hereof, up to 2,633,502 fully paid
         and nonassessable shares (such amount, as may be adjusted from
         time to time as set forth herein, the "Option Shares") of
         Common Stock, par value $10 per share ("Issuer Common Stock"),
         of the Issuer at a purchase price of U.S. $89.00 per Option
         Share (such price, as may be adjusted from time to time as set
         forth herein, the "Option Price").  The number of Option Shares







         that may be received upon the exercise of the Option and the
         Option Price are subject to adjustment as set forth in Section
         6.

                   2.  Exercise of Option.  (a)  Grantee may exercise
         the Option, in whole or part, at any time and from time to time
         on or after the date hereof if a Triggering Event (as defined
         below) shall have occurred; provided, however, that, to the
         extent the Option shall not have been exercised, it shall
         terminate and be of no further force and effect upon the ear-
         liest of (i) the Effective Time of the Merger, (ii) termination
         of the Merger Agreement pursuant to Section 7.01 thereof (other
         than for any of the reasons described in clause (iii) below) or
         (iii) 18 months after termination of the Merger Agreement (x)
         by either party under Section 7.01(c) or (d) thereof, (y) by
         Grantee under Section 7.01(b)(ii) thereof or (z) by Issuer
         under Section 7.01(b)(iv) under circumstances where Grantee
         could effect termination pursuant to Section 7.01(c); provided
         further that, any such exercise and purchase of Option Shares
         shall be subject to compliance with applicable laws, including
         the BHC Act.  The rights set forth in Sections 8, 9 and 10
         shall not terminate when the right to exercise the option
         terminates as set forth herein, but shall extend to such time
         as is provided in such Sections 8, 9 and 10.  Notwithstanding
         the termination of the Option, Grantee shall be entitled to
         purchase those Option Shares with respect to which it has ex-
         ercised the Option in accordance with the terms hereof prior to
         the termination of the Option.

                   (b)  A "Triggering Event" means the occurrence of an
         Acquisition Event, as defined in Section 5.07(b) of the Merger
         Agreement (without regard to whether the Merger Agreement is
         terminated).

                   (c)  Issuer shall notify Grantee promptly in writing
         of the occurrence of any Triggering Event; provided that it is
         understood that the giving of such notice by Issuer shall not
         be a condition to the right of Grantee to exercise the Option.

                   (d)  In the event Grantee is entitled to and wishes
         to exercise the Option, it shall send to Issuer a written no-
         tice (the date of which being referred to herein as the "Notice
         Date") specifying (i) the total number of Option Shares it will
         purchase pursuant to such exercise and (ii) a place and date
         not earlier than three business days nor later than 60 business
         days from the Notice Date for the closing of such purchase (a
         "Closing Date"); provided that if prior notification to or
         approval of the Federal Reserve Board (the "Federal Reserve")
         or any other Governmental Entity is required in connection with
         such purchase, Grantee shall promptly file the required notice


                                       -2-







         or application for approval and shall expeditiously process the
         same and the period of time that otherwise would run pursuant
         to this sentence shall run instead from the date on which, as
         the case may be, (A) any required notification periods have
         expired or been terminated or (B) such approvals have been
         obtained and any requisite waiting period or periods shall have
         passed.

                   (e)  Notwithstanding Section 3(d), in no event shall
         any Closing Date be more than 18 months after the related No-
         tice Date, and if the Closing Date shall not have occurred
         within 18 months after the related Notice Date due to the
         failure to obtain any such required approval, the exercise of
         the Option effected on the Notice Date shall be deemed to have
         expired.  In the event (i) Grantee receives official notice
         that an approval of the Federal Reserve or any other Govern-
         mental Entity required for the purchase of the Option Shares
         would not be issued or granted or (ii) a Closing Date shall not
         have occurred within 18 months after the related Notice Date
         due to the failure to obtain any such required approval,
         Grantee shall nevertheless be entitled to exercise its right as
         set forth in Section 8 or to exercise the Option in connection
         with the resale of Issuer Common Stock or other securities
         pursuant to a registration statement as provided in Section 10.
         The provisions of this Section 3 and Section 4 shall apply with
         appropriate adjustments to any such exercise.

                   4.  Payment and Delivery of Certificates.  (a)  On
         each Closing Date referred to in Section 3(d), Grantee shall
         pay to Issuer in immediately available funds by a wire transfer
         to a bank account designated by Issuer an amount equal to the
         Option Price multiplied by the number of Option Shares to be
         purchased on such Closing Date.

                   (b)  On each Closing Date, simultaneously with the
         delivery of immediately available funds as provided in Section
         4(a), Issuer shall deliver to Grantee a certificate or cer-
         tificates representing the Option Shares to be purchased on
         such Closing Date.  If the Option should be exercised in part
         only, a new Option evidencing the rights of Grantee to purchase
         the balance of the Option Shares purchasable hereunder shall be
         issued to Grantee, and Grantee shall deliver to Issuer a copy
         of this Agreement and a letter agreeing that Grantee will not
         offer to sell or otherwise dispose of such Option Shares in
         violation of applicable law or the provisions of this Agree-
         ment.

                   (c)  Certificates for Issuer Common Stock delivered
         on a Closing Date hereunder shall be endorsed with a restric-
         tive legend that shall read substantially as follows:


                                       -3-







              THE TRANSFER OF THE SHARES REPRESENTED BY THIS CERTIFICATE
              IS SUBJECT TO CERTAIN RESALE RESTRICTIONS ARISING UNDER
              THE SECURITIES ACT OF 1933, AS AMENDED, AND PURSUANT TO
              THE TERMS OF A STOCK OPTION AGREEMENT DATED AS OF FEBRUARY
              4, 1995, A COPY OF WHICH AGREEMENT IS ON FILE AT THE
              PRINCIPAL OFFICE OF ISSUER.  A COPY OF SUCH AGREEMENT WILL
              BE MAILED TO THE HOLDER HEREOF WITHOUT CHARGE UPON RECEIPT
              BY ISSUER OF A WRITTEN REQUEST THEREFOR.

         It is understood and agreed that:  (i) the reference to the
         resale restrictions of the Securities Act of 1933, as amended
         (the "Securities Act"), in the above legend shall be removed by
         delivery of substitute certificate(s) without such reference if
         Grantee shall have delivered to Issuer a copy of a letter from
         the staff of the Securities and Exchange Commission, or an
         opinion of counsel, in form and substance satisfactory to Is-
         suer, to the effect that such legend is not required for pur-
         poses of the Securities Act; (ii) the reference to the provi-
         sions of this Agreement in the above legend shall be removed by
         delivery of substitute certificate(s) without such reference if
         the Option Shares have been sold or transferred in compliance
         with the provisions of this Agreement and under circumstances
         that do not require the retention of such reference; and (iii)
         the legend shall be removed in its entirety if the conditions
         in the preceding clauses (i) and (ii) are both satisfied.  In
         addition, such certificates shall bear any other legend as may
         be required by law.

                   (d)  Upon the giving by Grantee to Issuer of the
         written notice of exercise of the Option provided for under
         Section 3(d), the tender of the applicable purchase price in
         immediately available funds and the tender of a copy of this
         Agreement to Issuer, Grantee shall be deemed to be the holder
         of record of the Option Shares issuable upon such exercise,
         notwithstanding that the stock transfer books of Issuer shall
         then be closed or that certificates representing such Option
         Shares shall not then be actually delivered to Grantee.  Issuer
         shall pay all expenses and any and all United States Federal,
         state and local taxes and other charges that may be payable in
         connection with the preparation, issue and delivery of stock
         certificates under this Section 4 in the name of Grantee or its
         assignee, transferee or designee.

                   (e)  If, at the time of issuance of any Option Shares
         pursuant to an exercise of all or a portion of the Option here-
         under, Issuer shall not have redeemed the Rights or shall have
         issued any similar securities, then each Option Share issued
         pursuant to such exercise shall also represent Rights or new
         rights with terms substantially identical to and at least



                                       -4-







         as favorable to Grantee as are provided under the Rights
         Agreement or any similar agreement then in effect.

                   5.  Authorizations, etc.  Issuer agrees (i) that it
         shall at all times maintain, free from preemptive rights or
         Liens, sufficient authorized but unissued shares of Issuer
         Common Stock so that the Option may be exercised without ad-
         ditional authorization of Issuer Common Stock after giving
         effect to all other options, warrants, convertible securities
         and other rights to purchase Issuer Common Stock, (ii) that it
         will not, by charter amendment or through reorganization, re-
         capitalization, reclassification, consolidation, merger, dis-
         solution or sale of assets, or by any other voluntary act,
         avoid or seek to avoid the observance or performance of any of
         the covenants, stipulations or conditions to be observed or
         performed hereunder by Issuer and (iii) promptly to take all
         action as may from time to time be required (including, in the
         event, under the BHC Act or the Change in Bank Control Act of
         1978, as amended, or a state banking law, prior approval of or
         notice to the Federal Reserve or to any state regulatory au-
         thority is necessary before the Option may be exercised, co-
         operating fully with Grantee in preparing such applications or
         notices and providing such information to the Federal Reserve
         or such state regulatory authority as they may require) in
         order to permit Grantee to exercise the Option and so that the
         Option Shares, when issued, shall be duly authorized, validly
         issued, fully paid and nonassessable and free and clear of all
         Liens and not subject to any preemptive rights.

                   6.  Adjustments.  (a)  In the event that any addi-
         tional shares of Issuer Common Stock are issued or otherwise
         become outstanding after the date of this Agreement (other than
         pursuant to an exercise of the Option or an event described in
         Section 6(b)), including pursuant to stock option plans and in
         connection with acquisitions and other transactions permitted
         by the Merger Agreement, the number of Option Shares shall be
         increased so that, after such issuance, it equals 19.9% of the
         number of shares of Issuer Common Stock then issued and out-
         standing (without giving pro forma effect to the issuance of
         the Option Shares).  Nothing contained in this Section 6(a) or
         elsewhere in this Agreement shall be deemed to authorize Issuer
         to issue shares of Issuer Common Stock in breach of, or oth-
         erwise breach any of, the provisions of the Merger Agreement.

                   (b)  In the event of any change in Issuer Common
         Stock by reason of a stock dividend, split-up, recapitaliza-
         tion, combination, subdivision, conversion, exchange of shares
         or similar transaction, the type and number of Option Shares
         shall be appropriately adjusted and proper provision shall be
         made in the agreements governing any such transaction, so that


                                       -5-







         Grantee shall receive upon exercise of the Option the number
         and class of shares, other securities, property or cash that
         Grantee would have received in respect of Issuer Common Stock
         if the Option had been exercised in full and the Option Shares
         had been issued to Grantee immediately prior to such event or
         the record date therefor, as applicable.  Whenever the number
         of Option Shares is adjusted as provided in this Section 6(b),
         the Option Price shall be adjusted by multiplying the Option
         Price by a fraction, the numerator of which is equal to the
         number of Option Shares purchasable prior to the adjustment and
         the denominator of which is equal to the number of Option
         Shares purchasable after the adjustment.

                   7.  Replacement Options.  (a)  In the event that
         Issuer shall enter into an agreement (i) to consolidate with or
         merge into any person, other than Grantee or one of its sub-
         sidiaries, and shall not be the continuing or surviving cor-
         poration of such consolidation or merger, (ii) to permit any
         person, other than Grantee or one of its subsidiaries, to merge
         into Issuer and Issuer shall be the continuing or surviving
         corporation, but, in connection with such merger, the then
         outstanding shares of Issuer Common Stock shall be changed into
         or exchanged for stock or other securities of Issuer or any
         other person or cash or any other property or the then out-
         standing shares of Issuer Common Stock shall after such merger
         represent less than 50% of the outstanding shares and share
         equivalents of the merged company or (iii) to sell or otherwise
         transfer all or substantially all its assets to any person,
         other than Grantee or one of its subsidiaries, then, and in
         each such case, the agreement governing such transaction shall
         make proper provision so that the Option shall, upon the con-
         summation of any such transaction and upon the terms and con-
         ditions set forth herein, be converted into, or exchanged for,
         an option (the "Substitute Option"), at the election of
         Grantee, of either (A) the Acquiring Corporation (as defined
         below) or (B) any person that controls the Acquiring Corpora-
         tion.

                   (b)  The following terms have the meanings indicated:

                   (i)  "Acquiring Corporation" shall mean (A) the con-
              tinuing or surviving corporation of a consolidation or
              merger with Issuer (if other than Issuer), (B) Issuer in a
              merger in which Issuer is the continuing or surviving
              person or (C) the transferee of all or substantially all
              of Issuer's assets.

                  (ii)  "Substitute Common Stock" shall mean the common
              stock issued by the issuer of the Substitute Option upon
              exercise of the Substitute Option.


                                       -6-







                 (iii)  "Average Price" shall mean the average closing
              price of a share of the Substitute Common Stock for the
              one year immediately preceding the consolidation, merger
              or sale in question, but in no event higher than the
              closing price of the shares of the Substitute Common Stock
              on the day preceding such consolidation, merger or sale;
              provided that, if Issuer is the issuer of the Substitute
              Option, the Average Price shall be computed with respect
              to a share of common stock issued by the person merging
              into Issuer or by any company which controls or is con-
              trolled by such person, as Grantee may elect.

                   (c)  The Substitute Option shall have the same terms
         as the Option, provided that, if the terms of the Substitute
         Option cannot, for legal reasons, be the same as the Option,
         such terms shall be as similar as possible and in no event less
         advantageous to Grantee.  The issuer of the Substitute Option
         (the "Substitute Option Issuer") shall also enter into an
         agreement with Grantee in substantially the same form as this
         Agreement, which shall be applicable to the Substitute Option.
         Without limiting the generality of the foregoing, the provi-
         sions of Sections 8, 9, 10, 11 and 12 shall apply with respect
         to the Substitute Option and any securities for which the
         Substitute Option becomes exercisable with the same effect as
         if all references to "Issuer" in such Sections were references
         to "Substitute Option Issuer", all references to "Issuer Common
         Stock" were references to "Substitute Common Stock", all ref-
         erences to the "Option" were references to the "Substitute
         Option" and all references to "Option Shares" were references
         to "Substitute Option Shares".

                   (d)  The Substitute Option shall be exercisable for
         such number of shares of Substitute Common Stock as is equal to
         the then-current Applicable Price (as defined in Section 8(c))
         multiplied by the number of shares of Issuer Common Stock for
         which the Option is then exercisable, divided by the then-
         current Average Price.  The exercise price of the Substitute
         Option per share of Substitute Common Stock shall then be equal
         to the Option Price multiplied by a fraction in which the nu-
         merator is the number of shares of Issuer Common Stock for
         which the Option is then exercisable and the denominator is the
         number of shares of the Substitute Common Stock for which the
         Substitute Option is exercisable.

                   (e)  In no event, pursuant to any of the foregoing
         paragraphs, shall the Substitute Option be exercisable for more
         than 19.9% of the shares of Substitute Common Stock outstanding
         prior to the exercise of the Substitute Option.  In the event
         that the Substitute Option would be exercisable for more than
         19.9% of the shares of Substitute Common Stock outstanding


                                       -7-







         prior to such exercise but for the limitation in this paragraph
         (e), the Substitute Option Issuer shall make a cash payment to
         Grantee equal to the excess of (i) the value of the Substitute
         Option without giving effect to the limitation in this para-
         graph (e) over (ii) the value of the Substitute Option after
         giving effect to the limitation in this paragraph (e).  This
         difference in value shall be determined by a nationally rec-
         ognized investment banking firm selected by Grantee.

                   (f)  Issuer shall not enter into any transaction de-
         scribed in Section 7(a) unless the Acquiring Corporation and
         any person that controls the Acquiring Corporation assume in
         writing all the obligations of Issuer hereunder.

                   8.  Repurchase at the Option of Grantee.  (a)  At the
         request of Grantee at any time during (i) the period during
         which the Option is exercisable pursuant to Section 3 or (ii)
         the period of 30 business days immediately following the oc-
         currence of either of the events set forth in clauses (i) and
         (ii) of the second sentence of Section 3(e) (but solely as to
         the shares of Issuer Common Stock with respect to which the
         required approval was not received) (either such period being
         referred to herein as the "Repurchase Period"), Issuer (or any
         successor entity thereof) shall repurchase from Grantee (A) the
         Option (or, in the circumstances set forth in clause (ii)
         above, that portion thereof relating to shares of Issuer Common
         Stock with respect to which required approvals were not re-
         ceived) unless the Option has expired or been terminated in
         accordance with the terms hereof and (B) all Option Shares
         purchased by Grantee pursuant hereto with respect to which
         Grantee then has beneficial ownership.  The date on which
         Grantee exercises its rights under this Section 8 is referred
         to as the "Request Date".  Such repurchase shall be at an ag-
         gregate price (the "Section 8 Repurchase Consideration") equal
         to the sum of:

                   (1)  the aggregate exercise price paid by Grantee for
              any Option Shares acquired with respect to which Grantee
              then has beneficial ownership;

                   (2)  the excess, if any, of (x) the Applicable Price
              for shares of Issuer Common Stock over (y) the Option
              Price, with such excess multiplied by the number of Option
              Shares with respect to which the Option has not been ex-
              ercised; and

                   (3)  the excess, if any, of (x) the Applicable Price
              over (y) the Option Price paid (or, in the case of Option
              Shares with respect to which the Option has been exercised
              but the Closing Date has not occurred, payable) by Grantee


                                       -8-







              for each Option Share with respect to which the Option has
              been exercised, with such excess multiplied by the number
              of such Option Shares.

                   (b)  If Grantee exercises its rights under this Sec-
         tion 8, Issuer shall, within 10 business days after the Request
         Date, pay the Section 8 Repurchase Consideration to Grantee in
         immediately available funds, and Grantee shall surrender to
         Issuer the Option and the certificates evidencing the shares of
         Issuer Common Stock purchased thereunder with respect to which
         Grantee then has beneficial ownership, and Grantee shall war-
         rant that it has sole record and beneficial ownership of such
         shares and that the same are then free and clear of all Liens.
         Notwithstanding the foregoing, to the extent that prior noti-
         fication to or approval of the Federal Reserve or other Gov-
         ernmental Entity is required in connection with the payment of
         all or any portion of the Section 8 Repurchase Consideration,
         Issuer shall deliver from time to time that portion of the
         Section 8 Repurchase Consideration that it is not then so
         prohibited from paying and shall promptly file the required
         notice or application for approval and shall expeditiously
         process the same (and Grantee shall cooperate with Issuer in
         the filing of any such notice or application and the obtaining
         of any such approval), and the period of time that otherwise
         would run pursuant to the preceding sentence for the payment of
         the portion of the Section 8 Repurchase Consideration requiring
         such notification or approval shall run instead from the date
         on which, as the case may be, (i) any required notification
         period has expired or been terminated or (ii) such approval has
         been obtained and, in either event, any requisite waiting pe-
         riod shall have passed.  If the Federal Reserve or any other
         Governmental Entity disapproves of any part of Issuer's pro-
         posed repurchase pursuant to this Section 8, Issuer shall
         promptly give notice of such fact to Grantee and redeliver to
         Grantee the Option Shares it is then prohibited from repur-
         chasing, and Grantee shall have the right to exercise the Op-
         tion as to the number of Option Shares for which the Option was
         exercisable at the Request Date less the number of shares as to
         which payment has been made pursuant to Section 8(a)(2); pro-
         vided that if the Option shall have terminated prior to the
         date of such notice or shall be scheduled to terminate prior to
         the date of such notice or shall be scheduled to terminate at
         any time before the expiration of a period ending on the 30th
         business day after such date, Grantee shall nonetheless have
         the right so to exercise the Option or exercise its rights
         under Section 10 until the expiration of such period of 30
         business days.  Notwithstanding anything herein to the con-
         trary, Grantee shall be entitled to exercise its right under
         this Section 8 on only one occasion.



                                       -9-







                   (c)  For purposes of this Agreement, the "Applicable
         Price" means the highest of (i) the highest price per share at
         which a tender offer or exchange offer has been made for shares
         of Issuer Common Stock after the date hereof and on or prior to
         the Request Date (or any other applicable determination date),
         (ii) the price per share to be paid by any third party for
         shares of Issuer Common Stock or the consideration per share to
         be received by holders of Issuer Common Stock, in each case
         pursuant to an agreement with Issuer for a merger or other
         business combination entered into on or prior to the Request
         Date (or any other applicable determination date), (iii) the
         highest price per share paid by any third party to acquire from
         a stockholder of Issuer, in one transaction or in a series of
         related transactions, an aggregate amount of Issuer Common
         Stock of 5% or more of the outstanding Issuer Common Stock or
         (iv) the highest bid price per share of Issuer Common Stock as
         quoted on the Nasdaq over-the-counter quotations system or, if
         not so quoted, on the principal trading market on which such
         shares are traded as reported by a recognized source during the
         60 business days preceding the Request Date (or any other ap-
         plicable determination date).  If the consideration to be of-
         fered, paid or received pursuant to a transaction described in
         either clause (i) or (ii) above shall be other than cash, the
         value of such consideration shall be determined in good faith
         by an independent nationally recognized investment banking firm
         selected by Grantee and reasonably acceptable to Issuer, which
         determination shall be conclusive for all purposes of this
         Agreement.

                   9.  Repurchase at the Option of Issuer.  (a)  Except
         to the extent that Grantee shall have previously exercised its
         rights under Section 8, at the request of Issuer during the
         six-month period commencing 15 months following the first oc-
         currence of a Triggering Event, Issuer may repurchase from
         Grantee, and Grantee shall sell to Issuer, all (but not less
         than all) the shares of Issuer Common Stock acquired by Grantee
         pursuant hereto and with respect to which Grantee has benefi-
         cial ownership at the time of such repurchase at a price equal
         to the greater of (i) 110% of the Current Market Price (as
         defined below) or (ii) the sum of (A) the Option Price in re-
         spect of the shares so acquired and (B) Grantee's pre-tax per
         share carrying cost (as defined below), multiplied in the case
         of either clause (i) or (ii) above by the number of shares so
         acquired (the "Section 9 Repurchase Consideration"); provided
         that Grantee, within 30 days following Issuer's notice of its
         intention to purchase shares pursuant to this Section 9, may
         deliver an Offeror's Notice (as defined in Section 11) pursuant
         to Section 11, in which case the provisions of Section 11 and
         not those of this Section 9 shall control; and provided further
         that Issuer's rights under this Section 9 shall be suspended


                                       -10-







         (with any such rights being extended accordingly) during any
         period when the exercise of such rights would subject Grantee
         to liability pursuant to Section 16(b) of the Exchange Act by
         reason of Grantee's purchase of shares of Issuer Common Stock
         pursuant to this Agreement.

                   (b)  If Issuer exercises its rights under this Sec-
         tion 9 and Grantee does not deliver an Offeror's Notice or
         Grantee does not sell the shares to a third party pursuant
         thereto, Issuer shall, within 10 business days after the ex-
         piration of the 30-day period referred to in paragraph (a)
         above or, if applicable, upon abandonment of the transaction
         covered by the Offeror's Notice, pay the Section 9 Repurchase
         Consideration in immediately available funds, and Grantee shall
         surrender to Issuer the certificates evidencing the shares of
         Issuer Common Stock purchased hereunder with respect to which
         Grantee then has beneficial ownership, and Grantee shall war-
         rant that it has sole record and beneficial ownership of such
         shares and that the same are then free and clear of all Liens.

                   (c)  As used herein, (i) "Current Market Price" means
         the average closing bid price per share of Issuer Common Stock
         as quoted on the Nasdaq over-the-counter quotations system or,
         if not so quoted, on the principal trading market on which such
         shares are traded as reported by a recognized source for the 10
         business days preceding the date of the Issuer's request for
         repurchase pursuant to this Section 9 and (ii) "Grantee's pre-
         tax per share carrying cost" shall be the amount equal to the
         interest on the aggregate Option Price paid for the shares of
         Issuer Common Stock purchased from the date of purchase to the
         date of repurchase at the rate of interest announced by
         Parent's New York branch as its prime or base lending or ref-
         erence rate during such period, less any dividends received on
         the shares so purchased, divided by the number of shares so
         purchased.

                   10.  Registration Rights; Listing.  (a)  Issuer shall,
         if requested by Grantee at any time and from time to time (i)
         within three years of the first exercise of the Option or (ii)
         for 30 business days following the occurrence of either of the
         events set forth in clauses (i) and (ii) of the second sentence
         of Section 3(e) or receipt by Grantee of official notice that
         an approval of the Federal Reserve or any other Governmental
         Entity required for a repurchase as contemplated by Section
         8(b) would not be issued or granted (but solely as to the
         shares of Issuer Common Stock or portion of the Option with
         respect to which the required approval was not received), as
         expeditiously as practicable prepare and file up to two
         registration statements under the Securities Act if necessary
         in order to permit the sale or other disposition of the shares


                                       -11-







         of Issuer Common Stock or other securities that have been ac-
         quired by or are issuable to Grantee upon exercise of the Op-
         tion in accordance with the intended method of sale or other
         disposition stated by Grantee, including a "shelf" registration
         statement under Rule 415 under the Securities Act or any suc-
         cessor provision.  Issuer shall use its best efforts to cause
         each such registration statement to become effective and to
         remain effective for such period not in excess of 180 days from
         the day such registration statement first becomes effective as
         may be reasonably necessary to effect such sale or other dis-
         position.  Issuer shall also use its best efforts to qualify
         such shares or other securities under any applicable state
         securities laws.  Grantee agrees to use all reasonable efforts
         to cause, and to cause any underwriters or agents of any sale
         or other disposition to cause, any sale or other disposition
         pursuant to such registration statement to be effected on a
         widely distributed basis so that upon consummation thereof no
         purchaser or transferee shall own beneficially more than 2% of
         the then outstanding voting power of Issuer.  In the event that
         Grantee requests Issuer to file a registration statement fol-
         lowing the failure to obtain a required approval for an exer-
         cise of the Option as described in Section 3(e), the closing of
         the sale or other disposition of Issuer Common Stock or other
         securities pursuant to such registration statement shall occur
         substantially simultaneously with the exercise of the Option,
         and Grantee shall be entitled to cause the Option Shares to be
         issued directly to the underwriters or agents named in such
         registration statement.  The obligations of Issuer hereunder to
         file a registration statement and to maintain its effectiveness
         may be suspended for one or more periods of time that do not
         exceed 60 days in the aggregate for all such periods if the
         Board of Directors of Issuer shall have determined that the
         filing of such registration statement or the maintenance of its
         effectiveness would require disclosure of nonpublic information
         that would materially and adversely affect Issuer.  Any regis-
         tration effected under this Section 10 shall be at Issuer's ex-
         pense, except for underwriting discounts or commissions,
         brokers' fees and the fees and disbursements of Grantee's
         counsel related thereto.  Grantee shall provide all information
         reasonably requested by Issuer for inclusion in any registra-
         tion statement to be filed hereunder.  If requested by Grantee
         in connection with any such registration, Issuer shall become a
         party to any underwriting agreement relating to the sale of
         such shares or other securities, but only to the extent of
         obligating itself in respect of representations, warranties,
         covenants, indemnities, contribution and other agreements
         customarily included in such underwriting agreements for the
         issuer.  If, during the time periods referred to in the first
         sentence of this Section 10, Issuer effects a registration
         under the Securities Act of Issuer Common Stock for its own


                                       -12-







         account or for any other stockholders of Issuer (other than on
         Form S-4 or S-8, or any successor form), it shall allow Grantee
         the right to participate in such registration, and such par-
         ticipation shall not affect the obligation of Issuer to effect
         two registration statements for Grantee under this Section 10;
         provided that, if the managing underwriters of such offering
         advise Issuer in writing that in their opinion the number of
         shares of Issuer Common Stock requested to be included in such
         registration exceeds the number which can be sold in such of-
         fering, Issuer shall include the shares requested to be in-
         cluded therein by Grantee pro rata with the shares intended to
         be included therein by Issuer or other stockholders, taken as a
         single group.

                   (b)  If Issuer Common Stock or any other securities
         to be acquired upon exercise of the Option are then listed on a
         national or regional securities exchange or quoted on a na-
         tional or regional quotation system, Issuer, upon request of
         Grantee, shall use its best efforts to make any filings and
         obtain any approvals necessary in order to cause the Option
         Shares or other securities acquired upon exercise of the Option
         to be so listed or quoted.

                   11.  First Refusal.  At any time after the first oc-
         currence of a Triggering Event and prior to the later of (a)
         expiration of 24 months immediately following the first pur-
         chase of shares of Issuer Common Stock pursuant to the Option
         and (b) the termination of the Option pursuant to Section 3(a),
         if Grantee shall desire to sell, assign, transfer or otherwise
         dispose of all or any of the shares of Issuer Common Stock or
         other securities acquired by it pursuant to the Option, it
         shall give Issuer written notice of the proposed transaction
         (an "Offeror's Notice"), identifying the proposed transferee,
         accompanied by a copy of a binding offer to purchase such
         shares or other securities from such transferee and setting
         forth the terms of the proposed transaction.  An Offeror's
         Notice shall be deemed an offer by Grantee to Issuer, which may
         be accepted within 10 business days of the receipt of such
         Offeror's Notice, on the same terms and conditions and at the
         same price at which Grantee is proposing to transfer such
         shares or other securities to such transferee.  The purchase of
         any such shares or other securities by Issuer shall be settled
         within 10 business days of the date of the acceptance of the
         offer and the purchase price shall be paid to Grantee in im-
         mediately available funds; provided that, if prior notification
         to or approval of the Federal Reserve or any other Governmental
         Entity is required in connection with such purchase, Issuer
         shall promptly file the required notice or application for
         approval and shall expeditiously process the same (and Grantee
         shall cooperate with Issuer in the filing of any such notice or


                                       -13-







         application and the obtaining of any such approval) and the
         period of time that otherwise would run pursuant to this sen-
         tence shall run instead from the date on which, as the case may
         be, (i) any required notification period has expired or been
         terminated or (ii) such approval has been obtained and, in
         either event, any requisite waiting period shall have passed.
         In the event of the failure or refusal of Issuer to purchase
         all the shares or other securities covered by an Offeror's
         Notice or if the Federal Reserve or any other Governmental
         Entity disapproves Issuer's proposed purchase of such shares or
         other securities, Grantee may, within 60 days from the date of
         the Offeror's notice (subject to any necessary extension for
         regulatory notification, approval or waiting periods), sell
         all, but not less than all, of such shares or other securities
         to the proposed transferee at no less than the price specified,
         and on terms no more favorable than those specified, in the
         Offeror's Notice.  The requirements of this Section 11 shall
         not apply to (A) any disposition as a result of which the
         proposed transferee would own beneficially not more than 2% of
         the outstanding voting power of Issuer, (B) any disposition of
         Issuer Common Stock or other securities by a person to whom
         Grantee has assigned its rights under the Option with the
         consent of Issuer, (C) any sale by means of a public offering
         registered under the Securities Act in which steps are taken to
         reasonably assure that no purchaser will acquire securities
         representing more than 2% of the outstanding voting power of
         Issuer or (D) any transfer to Sub or to any other wholly owned
         subsidiary of Parent that agrees in writing to be bound by the
         terms hereof.

                   12.  Division of Option.  This Agreement (and the
         Option granted hereby) are exchangeable, without expense, at
         the option of Grantee, upon presentation and surrender of this
         Agreement at the principal office of Issuer, for other Agree-
         ments providing for Options of different denominations enti-
         tling the holder thereof to purchase in the aggregate the same
         number of shares of Issuer Common Stock purchasable hereunder.
         The terms "Agreement" and "Option" as used herein include any
         Stock Option Agreements and related Options for which this
         Agreement (and the Option granted hereby) may be exchanged.
         Upon receipt by Issuer of evidence reasonably satisfactory to
         it of the loss, theft, destruction or mutilation of this
         Agreement, and (in the case of loss, theft, or destruction) of
         reasonably satisfactory indemnification, and upon surrender and
         cancellation of this Agreement, if mutilated, Issuer will ex-
         ecute and deliver a new Agreement of like tenor and date. Any
         such new Agreement executed and delivered shall constitute an
         additional contractual obligation on the part of Issuer,
         whether or not the Agreement so lost, stolen, destroyed, or
         mutilated shall at any time be enforceable by anyone.


                                       -14-







                   13.  Assignment.  Neither this Agreement nor any of
         the rights, interests or obligations under this Agreement or
         the Option shall be assigned by any of the parties hereto
         (whether by operation of law or otherwise) without the prior
         written consent of the other parties, except that Grantee may
         assign in whole or in part its rights and obligations hereunder
         to Sub or to any other direct or indirect wholly owned sub-
         sidiary of Grantee without the consent of Issuer.  Subject to
         the preceding sentence, the terms and conditions of this
         Agreement shall inure to the benefit of and be binding upon the
         parties hereto and their respective successors and permitted
         assigns.

                   14.  Further Assurances.  Each party hereto will use
         its best efforts to make all filings with, and to obtain con-
         sent of, all third parties and governmental authorities nec-
         essary or advisable to the consummation of the transactions
         contemplated by this Agreement, including applying to the
         Federal Reserve under the BHC Act for approval to acquire the
         shares issuable hereunder.  In the event of any exercise of the
         Option by Grantee, Issuer, Grantee and Sub shall execute and
         deliver all other documents and instruments and take all other
         action that may be reasonably necessary or advisable in order
         to consummate the transactions provided for by such exercise.

                   15.  Specific Performance.  The parties hereto ac-
         knowledge that damages would be an inadequate remedy for a
         breach of this Agreement by either party hereto and that the
         obligations of the parties hereto shall be enforceable by ei-
         ther party hereto through specific performance, injunctive
         relief or other equitable relief.  This provision is without
         prejudice to any other rights that the parties hereto may have
         for any failure to perform this Agreement.

                   16.  Severability.  If any term, provision, covenant
         or restriction contained in this Agreement is held by a court
         or a Federal or state regulatory agency of competent juris-
         diction to be invalid, void or unenforceable, the remainder of
         the terms, provisions, covenants and restrictions contained in
         this Agreement shall remain in full force and effect and shall
         in no way be affected, impaired or invalidated.  If for any
         reason such court or regulatory agency determines that Grantee
         is not permitted to acquire, or Issuer is not permitted to
         repurchase pursuant to Section 8, the full number of Option
         Shares provided in Section 1(a) hereof (as adjusted pursuant to
         Section 6), it is the express intention of Issuer to allow
         Grantee to acquire or to require Issuer to repurchase such
         lesser number of Option Shares as may be permissible without
         any amendment or modification hereof.



                                       -15-







                   17.  Notices.  All notices, requests, claims, demands
         and other communications hereunder shall be deemed to have been
         duly given when delivered in the manner and to the addresses
         specified in accordance with Section 8.02 of the Merger
         Agreement.

                   18.  Governing Law.  This Agreement shall be governed
         by and construed in accordance with the laws of the State of
         Michigan without regard to any applicable principles of con-
         flicts of laws.

                   19.  Counterparts.  This Agreement may be executed in
         one or more counterparts, all of which shall be considered one
         and the same agreement and shall become effective when one or
         more counterparts have been signed by each of the parties and
         delivered to the other parties.

                   20.  Expenses.  Except as otherwise expressly pro-
         vided herein, each of the parties hereto shall bear and pay all
         costs and expenses incurred by it or on its behalf in connec-
         tion with the transactions contemplated hereunder, including
         fees and expenses of its own financial consultants, investment
         bankers, accountants and counsel.

                   21.  Limitation on Maximum Gain.  Notwithstanding
         anything to the contrary contained herein or in the Merger
         Agreement, the aggregate amount of gain realized by Grantee
         pursuant to this Stock Option Agreement from Issuer (or the
         Substitute Option Issuer), when added to the Termination Fee
         (as defined in Section 5.07(b) of the Merger Agreement), if
         any, received by Grantee pursuant to such Section 5.07(b),
         shall not in the aggregate exceed U.S. $75,000,000, and, in the
         event Grantee realizes gain in excess of such amount hereunder
         from Issuer (or the Substitute Option Issuer) or under the
         Termination Fee, Grantee hereby undertakes promptly to pay back
         to Issuer, by wire transfer of immediately available funds, the
         amount of such excess.

                   22.  Waiver and Amendment.  Any provision of this
         Agreement may be waived at any time by the party that is en-
         titled to the benefits of such provision.  This Agreement may
         not be modified, amended, altered or supplemented except upon
         the execution and delivery of a written agreement executed by
         the parties hereto.

                   23.  Entire Agreement; No Third-Party Beneficiaries.
         Except as otherwise expressly provided herein or in the Merger
         Agreement, this Agreement (and the Merger Agreement and the
         other documents and instruments referred to herein and therein)
         contains the entire agreement between the parties with respect


                                       -16-







         to the transactions contemplated hereunder and supersedes all
         prior arrangements or understandings with respect thereof,
         written or oral.  Nothing in this Agreement, expressed or im-
         plied, is intended to confer upon any party, other than the
         parties hereto, and their respective successors and permitted
         assigns, any rights, remedies, obligations or liabilities under
         or by reason of this Agreement, except as expressly provided
         herein.


                   IN WITNESS WHEREOF, each of the parties has caused
         this Agreement to be executed on its behalf by its officers
         thereunto duly authorized, all as of the day and year first
         above written.


                                       NATIONAL AUSTRALIA BANK
                                       LIMITED A.C.N. 004044937,

                                         by
                                           /s/ Bruce S. McComish        
                                           Name:  Bruce S. McComish
                                           Title:  Chief Financial
                                                     Officer


                                       MNC ACQUISITION CO.

                                         by
                                           /s/ Bruce S. McComish        
                                           Name:  Bruce S. McComish
                                           Title:  Chairman, President
                                                     and Chief Executive
                                                     Officer


                                       MICHIGAN NATIONAL CORPORATION

                                         by
                                           /s/ Robert J. Mylod          
                                           Name:  Robert J. Mylod
                                           Title:  Chairman and Chief
                                                     Executive Officer









                                       -17-