<PAGE>   1
                                                                     EXHIBIT 4.2

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                               GUARANTEE AGREEMENT


                            DATED AS OF JULY 31, 2001


                                 BY AND BETWEEN


                             COMERICA INCORPORATED,
                                  AS GUARANTOR


                                       AND


              CHASE MANHATTAN TRUST COMPANY, NATIONAL ASSOCIATION,
                                   AS TRUSTEE






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<PAGE>   2




                            CROSS REFERENCE TABLE(1)

<TABLE>
<CAPTION>
Section of Trust                                                                                         Section of
Indenture Act of                                                                                          Guarantee
1939, as amended                                                                                          Agreement
----------------                                                                                          ---------
<S>                                                                                                  <C>
310(a).......................................................................................................4.1(a)
310(b)..................................................................................................2.8; 4.1(c)
310(c).................................................................................................Inapplicable
311(a).......................................................................................................2.2(b)
311(b).......................................................................................................2.2(b)
311(c).................................................................................................Inapplicable
312(a)..................................................................................................2.2(a); 2.9
312(b)..................................................................................................2.2(b); 2.9
312(c)..........................................................................................................2.9
313(a)..........................................................................................................2.3
313(b)..........................................................................................................2.3
313(c)..........................................................................................................2.3
313(d)..........................................................................................................2.3
314(a)..........................................................................................................2.4
314(b).................................................................................................Inapplicable
314(c)..........................................................................................................2.5
314(d).................................................................................................Inapplicable
314(e)..........................................................................................................2.5
314(f).................................................................................................Inapplicable
315(a)...............................................................................................3.1(d); 3.2(a)
315(b).......................................................................................................2.7(a)
315(c).......................................................................................................3.1(c)
315(d).......................................................................................................3.1(d)
316(a)..................................................................................................2.6; 5.4(a)
316(b)......................................................................................................... 5.3
316(c)................................................................................................ Inapplicable
317(a).........................................................................................................2.10
317(b).................................................................................................Inapplicable
318(a).......................................................................................................2.1(b)
</TABLE>


--------
(1)      This Cross-Reference Table does not constitute part of the Agreement
         and shall not have any bearing upon the interpretation of any of its
         terms or provisions.


<PAGE>   3


                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                                                PAGE
<S>                                                                                                             <C>
ARTICLE 1 INTERPRETATION AND DEFINITIONS..........................................................................1

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

ARTICLE 2 TRUST INDENTURE ACT.....................................................................................5

         SECTION 2.1.               Trust Indenture Act; Application..............................................5

         SECTION 2.2.               Lists of Holders of Securities................................................5

         SECTION 2.3.               Reports by Guarantee Trustee..................................................5

         SECTION 2.4.               Periodic Reports to Guarantee Trustee.........................................5

         SECTION 2.5.               Evidence of Compliance with Conditions Precedent..............................5

         SECTION 2.6.               Guarantee Event of Default; Waiver............................................6

         SECTION 2.7.               Guarantee Event of Default; Notice............................................6

         SECTION 2.8.               Conflicting Interests.........................................................6

         SECTION 2.9.               Disclosure of Information.....................................................6

         SECTION 2.10.              Guarantee Trustee May File Proofs of Claim....................................6

ARTICLE 3 POWERS, DUTIES AND RIGHTS OF GUARANTEE TRUSTEE..........................................................7

         SECTION 3.1.               Powers and Duties of Guarantee Trustee........................................7

         SECTION 3.2.               Certain Rights of Guarantee Trustee...........................................8

         SECTION 3.3.               Not Responsible for Recitals or Issuance of Guarantee........................10

ARTICLE 4 GUARANTEE TRUSTEE......................................................................................10

         SECTION 4.1.               Guarantee Trustee; Eligibility...............................................10

         SECTION 4.2.               Appointment, Removal and Resignation of Guarantee Trustee....................11

ARTICLE 5 GUARANTEE..............................................................................................12

         SECTION 5.1.               Guarantee....................................................................12
</TABLE>


<PAGE>   4

<TABLE>
<S>                                                                                                              <C>
         SECTION 5.2.               Waiver of Notice and Demand..................................................12

         SECTION 5.3.               Obligations Not Affected.....................................................12

         SECTION 5.4.               Rights of Holders............................................................13

         SECTION 5.5.               Guarantee of Payment.........................................................13

         SECTION 5.6.               Subrogation..................................................................14

         SECTION 5.7.               Independent Obligations......................................................14

         SECTION 5.8.               Waiver Under Indenture and Debentures........................................14

ARTICLE 6 LIMITATION OF TRANSACTIONS; SUBORDINATION..............................................................14

         SECTION 6.1.               Limitation of Transactions...................................................14

         SECTION 6.2.               Ranking......................................................................15

         SECTION 6.3.               Subordination of Common Securities...........................................15

ARTICLE 7 TERMINATION............................................................................................15

ARTICLE 8 INDEMNIFICATION........................................................................................15

         SECTION 8.1.               Exculpation..................................................................15

         SECTION 8.2.               Indemnification..............................................................16

ARTICLE 9 MISCELLANEOUS..........................................................................................16

         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
</TABLE>



<PAGE>   5
                               GUARANTEE AGREEMENT


                  This GUARANTEE AGREEMENT (the "Guarantee"), dated as of July
31, 2001, is executed and delivered by COMERICA INCORPORATED, a Delaware
corporation (the "Guarantor"), and CHASE MANHATTAN TRUST COMPANY, NATIONAL
ASSOCIATION, a national banking association, as trustee (the "Guarantee
Trustee"), for the benefit of the Holders (as defined herein) from time to time
of the Securities (as defined herein) of COMERICA CAPITAL TRUST I, a Delaware
statutory business trust (the "Trust").

                                    RECITALS

                  WHEREAS, pursuant to the Declaration (as defined herein), the
Trust may issue up to $350,000,000 aggregate liquidation amount of preferred
securities, having a liquidation amount of $25 per security and designated the
"7.60% Preferred Securities" of the Trust (the "Preferred Securities") and up to
$10,824,750 aggregate liquidation amount of common securities, having a
liquidation amount of $25 per security and designated the "7.60% Common
Securities" of the Trust (the "Common Securities" and, together with the
Preferred Securities, the "Securities");

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

                  WHEREAS, if a Trust Enforcement Event (as defined herein) has
occurred and is continuing, the rights of Holders of the Common Securities to
receive Guarantee Payments (as defined herein) under this Guarantee are
subordinated to the rights of Holders of Preferred Securities to receive
Guarantee Payments under this Guarantee;

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

                                   ARTICLE 1

                         INTERPRETATION AND DEFINITIONS

         SECTION 1.1. Interpretation and Definitions. In this Guarantee, unless
the context otherwise requires:

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

                  (b) a term defined anywhere in this Guarantee has the same
         meaning throughout;


<PAGE>   6

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

                  (d) all references in this Guarantee to Articles, Sections and
         Recitals are to Articles, Sections and Recitals of this Guarantee,
         unless otherwise specified;

                  (e) unless otherwise defined in this Guarantee, a term defined
         in the Trust Indenture Act has the same meaning when used in this
         Guarantee;

                  (f) a reference to the singular includes the plural and vice
         versa and a reference to any masculine form of a term shall include the
         feminine form of a term, as applicable; and

                  (g) the following terms have the following meanings:

                  "Affiliate" has the same meaning as given to that term in Rule
405 of the Securities Act of 1933, as amended, or any successor rule thereunder.

                  "Business Day" has the meaning specified in the Declaration.

                  "Common Securities" has the meaning specified in the Recitals
hereto.

                  "Corporate Trust Office" means the principal office of the
Guarantee Trustee at which at any particular time its corporate trust business
shall be administered, which office at the date of execution of this Guarantee
is located at 250 West Huron Road, Suite 220, Cleveland, Ohio 44113.

                  "Covered Person" means a Holder or beneficial owner of
Securities.

                  "Debentures" means the series of junior subordinated
debentures to be issued by Comerica Incorporated designated the "7.60% Junior
Subordinated Debentures due 2050", held by the Property Trustee as defined in
the Declaration.

                  "Declaration" means the Amended and Restated Declaration of
Trust, dated as of the date hereof, as amended, modified or supplemented from
time to time, among the trustees of the Trust named therein, the Guarantor, as
sponsor, and the Holders, from time to time, of undivided beneficial ownership
interests in the assets of the Trust.

                  "Global Security" means a fully registered, global Preferred
Security, as defined in the Indenture, representing the Preferred Securities.

                  "Guarantee Event of Default" means a default by the Guarantor
on any of its payment or other obligations under this Guarantee.

                  "Guarantee Payments" means the following payments or
distributions, without duplication, with respect to the Securities, to the
extent not paid by or on behalf of the Trust: (i) any accumulated and unpaid
Distributions (as defined in the Declaration) that are required to be paid on
such Securities to the extent the Trust has sufficient funds available therefor
at the



                                       2
<PAGE>   7

time, (ii) the redemption price, including all accumulated and unpaid
Distributions to the date of redemption, with respect to any Securities called
for redemption by the Trust, to the extent the Trust shall have sufficient funds
available therefor at the time or (iii) upon a voluntary or involuntary
dissolution, winding-up or termination of the Trust (other than in connection
with the distribution of Debentures to the Holders in exchange for Securities as
provided in the Declaration), the lesser of (a) the aggregate of the liquidation
amount and all accumulated and unpaid Distributions on the Securities to the
date of payment, to the extent the Trust has sufficient funds available therefor
and (b) the amount of assets of the Trust remaining available for distribution
to Holders in liquidation of the Trust (in either case, the "Liquidation
Distribution").

                  "Guarantee Trustee" means Chase Manhattan Trust Company,
National Association, until a Successor Guarantee Trustee has been appointed and
has accepted such appointment pursuant to the terms of this Guarantee and
thereafter means each such Successor Guarantee Trustee.

                  "Holder" means any holder of Securities, as registered on the
books and records of the Trust; 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 or any other obligor on the
Preferred Securities.

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

                  "Indenture" means the Indenture, dated as of the date hereof,
by and between Comerica Incorporated and Chase Manhattan Trust Company, National
Association, as Trustee, and by any indenture supplemental thereto pursuant to
which the Debentures are to be issued to the Property Trustee, as defined in the
Declaration.

                  "List of Holders" has the meaning assigned to it in Section
2.2 hereof.

                  "Majority in Liquidation Amount" means, except as provided in
the terms of the Preferred Securities or by the Trust Indenture Act, Holder(s)
of outstanding Securities, voting together as a single class, or, as the context
may require, Holders of outstanding Preferred Securities or Holders of
outstanding Common Securities, voting separately as a class, who are the record
owners of more than 50% of the aggregate liquidation amount (including the
stated amount that would be paid on redemption, liquidation or otherwise, plus
accumulated and unpaid Distributions to the date upon which the voting
percentages are determined) of all outstanding Securities of the relevant class.
In determining whether the Holders of the requisite amount of Securities have
voted, Securities which are owned by the Guarantor or any Affiliate of the
Guarantor or any other obligor on the Securities shall be disregarded for the
purpose of any such determination.

                  "Officers' Certificate" means, with respect to any Person, a
certificate signed on behalf of such Person by two Authorized Officers (as
defined in the Declaration) of such Person.



                                       3
<PAGE>   8
Any Officers' Certificate delivered with respect to compliance with a condition
or covenant provided for in this Guarantee shall include:

                           (i) a statement that each officer signing the
                  Officers' Certificate has read the covenant or condition and
                  the definitions relating thereto;

                           (ii) a brief statement of the nature and scope of the
                  examination or investigation undertaken by each officer on
                  behalf of such Person in rendering the Officers' Certificate;

                           (iii) a statement that each such officer has made
                  such examination or investigation as, in such officer's
                  opinion, is necessary to enable such officer on behalf of such
                  Person to express an informed opinion as to whether or not
                  such covenant or condition has been complied with; and

                           (iv) a statement as to whether, in the opinion of
                  each such officer acting on behalf of such Person, such
                  condition or covenant has been complied with.

                  "Person" means a legal person, including any individual,
corporation, estate, partnership, joint venture, association, joint stock
company, limited liability company, trust, unincorporated association, or
government or any agency or political subdivision thereof, or any other entity
of whatever nature.

                  "Preferred Securities" has the meaning specified in the
Recitals hereto.

                  "Redemption Price" has the meaning specified in the
Declaration.

                  "Responsible Officer" means, with respect to the Guarantee
Trustee, any officer with direct responsibility for the administration of this
Guarantee 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.

                  "Securities" has the meaning specified in the Recitals hereto.

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

                  "Trust Enforcement Event" in respect of the Securities means
an Indenture Event of Default (as defined in the Indenture) has occurred and is
continuing in respect of the Debentures.

                  "Trust Indenture Act" means the Trust Indenture Act of 1939,
as amended from time to time, or any successor legislation.


                                       4
<PAGE>   9

                                   ARTICLE 2

                               TRUST INDENTURE ACT

         SECTION 2.1. Trust Indenture Act; Application. (a) This Guarantee is
subject to the provisions of the Trust Indenture Act that are required to be
part of this Guarantee and shall, to the extent applicable, be governed by such
provisions.

                  (b) If and to the extent that any provision of this 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 of Securities. (a) The Guarantor shall
provide the Guarantee Trustee (i) except while the Preferred Securities are
represented by one or more Global Securities at least one Business Day prior to
the date for payment of Distributions, a list, in such form as the Guarantee
Trustee may reasonably require, of the names and addresses of the Holders of the
Securities ("List of Holders") as of the record date relating to the payment of
such Distributions, and (ii) at any other time, within 30 days of receipt by the
Guarantor of a written request from the Guarantee Trustee for a List of Holders
as of a date no more than 15 days before such List of Holders is given to the
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 Guarantee Trustee by the Guarantor. The
Guarantee Trustee shall preserve, in as current a form as is reasonably
practicable, all information contained in Lists of Holders given to it, provided
that the Guarantee Trustee may destroy any List of Holders previously given to
it on receipt of a new List of Holders.

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

         SECTION 2.3. Reports by Guarantee Trustee. Within 60 days after May 15
of each year (commencing with the year of the first anniversary of the issuance
of the Securities), the Guarantee Trustee shall provide to the Holders of the
Securities 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 Guarantee Trustee shall also comply with the requirements of
Section 313(d) of the Trust Indenture Act.

         SECTION 2.4. Periodic Reports to Guarantee Trustee. The Guarantor shall
provide to the Guarantee Trustee such documents, reports and information as
required by Section 314(a) (if any) of the Trust Indenture Act and the
compliance certificate required by Section 314(a) of the Trust Indenture Act in
the form, in the manner and at the times required by Section 314(a) of the Trust
Indenture Act, but in no event later than 120 days after the end of each
calendar year.

         SECTION 2.5. Evidence of Compliance with Conditions Precedent. The
Guarantor shall provide to the Guarantee Trustee such evidence of compliance
with any conditions precedent, if any, provided for in this 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.





                                       5
<PAGE>   10
         SECTION 2.6. Guarantee Event of Default; Waiver. The Holders of a
Majority in Liquidation Amount of the Preferred Securities may, by vote or
written consent, on behalf of the Holders of all of the Securities, waive any
past Guarantee Event of Default and its consequences. Upon such waiver, any such
Guarantee Event of Default shall cease to exist, and any Guarantee Event of
Default arising therefrom shall be deemed to have been cured, for every purpose
of this Guarantee, but no such waiver shall extend to any subsequent or other
default or Guarantee Event of Default or impair any right consequent thereon.

         SECTION 2.7. Guarantee Event of Default; Notice. (a) The Guarantee
Trustee shall, within 90 days after the occurrence of a Guarantee Event of
Default actually known to a Responsible Officer of the Guarantee Trustee,
transmit by mail, first class postage prepaid, to the Holders of the Securities,
notices of all such Guarantee Events of Default, unless such defaults have been
cured before the giving of such notice; provided, that the Guarantee Trustee
shall be protected in withholding such notice if and so long as a Responsible
Officer of the Guarantee Trustee in good faith determines that the withholding
of such notice is in the interests of the Holders of the Securities.

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

         SECTION 2.8. Conflicting Interests. The Declaration shall be deemed to
be specifically described in this Guarantee for the purposes of clause (i) of
the first proviso contained in Section 310(b) of the Trust Indenture Act.

         SECTION 2.9. Disclosure of Information. The disclosure of information
as to the names and addresses of the Holders of the Securities in accordance
with Section 312 of the Trust Indenture Act, regardless of the source from which
such information was derived, shall not be deemed to be a violation of any
existing law, or any law hereafter enacted which does not specifically refer to
Section 312 of the Trust Indenture Act, nor shall the Guarantee Trustee be held
accountable by reason of mailing any material pursuant to a request made under
Section 312(b) of the Trust Indenture Act.

         SECTION 2.10. Guarantee Trustee May File Proofs of Claim. Upon the
occurrence of a Guarantee Event of Default, the Guarantee Trustee is hereby
authorized to (a) recover judgment, in its own name and as trustee of an express
trust, against the Guarantor for the whole amount of any Guarantee Payments
remaining unpaid and (b) file such proofs of claim and other papers or documents
as may be necessary or advisable in order to have its claims and those of the
Holders of the Securities allowed in any judicial proceedings relative to the
Guarantor, its creditors or its property.




                                       6
<PAGE>   11

                                   ARTICLE 3

                          POWERS, DUTIES AND RIGHTS OF
                                GUARANTEE TRUSTEE

         SECTION 3.1. Powers and Duties of Guarantee Trustee. This Guarantee
shall be held by the Guarantee Trustee on behalf of the Trust for the benefit of
the Holders of the Securities, and the Guarantee Trustee shall not transfer this
Guarantee to any Person except a Holder of Securities exercising his or her
rights pursuant to Section 5.4(b) or to a Successor Guarantee Trustee on
acceptance by such Successor Guarantee Trustee of its appointment to act as
Successor Guarantee Trustee. The right, title and interest of the Guarantee
Trustee in and to this Guarantee shall automatically vest in any Successor
Guarantee Trustee, and such vesting and succession of title shall be effective
whether or not conveyance documents have been executed and delivered pursuant to
the appointment of such Successor Guarantee Trustee.

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

                  (b) The Guarantee Trustee, before the occurrence of any
Guarantee Event of Default and after the curing of all Guarantee Events of
Default that may have occurred, shall undertake to perform only such duties as
are specifically set forth in this Guarantee, and no implied covenants shall be
read into this Guarantee against the Guarantee Trustee. In case a Guarantee
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 Guarantee
Trustee, the Guarantee Trustee shall exercise such of the rights and powers
vested in it by this Guarantee, and 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.

                  (c) No provision of this Guarantee shall be construed to
relieve the 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 Guarantee Event of
                  Default and after the curing or waiving of all such Guarantee
                  Events of Default that may have occurred:

                                    (A)      the duties and obligations of the
                                             Guarantee Trustee shall be
                                             determined solely by the express
                                             provisions of this Guarantee, and
                                             the Guarantee Trustee shall not be
                                             liable except for the performance
                                             of such duties and obligations as
                                             are specifically set forth in this
                                             Guarantee, and no implied covenants
                                             or obligations shall be read into
                                             this Guarantee against the
                                             Guarantee Trustee; and

                                    (B)      in the absence of bad faith on the
                                             part of the Guarantee Trustee, the
                                             Guarantee Trustee may conclusively
                                             rely, as to



                                       7
<PAGE>   12

                                             the truth of the statements and the
                                             correctness of the opinions
                                             expressed therein, upon any
                                             certificates or opinions furnished
                                             to the Guarantee Trustee and
                                             conforming to the requirements of
                                             this Guarantee; but in the case of
                                             any such certificates or opinions
                                             that by any provision hereof are
                                             specifically required to be
                                             furnished to the Guarantee Trustee,
                                             the Guarantee Trustee shall be
                                             under a duty to examine the same to
                                             determine whether or not they
                                             conform to the requirements of this
                                             Guarantee;

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

                           (iii) the 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
                  Securities relating to the time, method and place of
                  conducting any proceeding for any remedy available to the
                  Guarantee Trustee, or exercising any trust or power conferred
                  upon the Guarantee Trustee under this Guarantee; and

                           (iv) no provision of this Guarantee shall require the
                  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 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 Guarantee
                  or if the Guarantee Trustee shall have reasonable grounds for
                  believing that an indemnity, reasonably satisfactory to the
                  Guarantee Trustee, against such risk or liability is not
                  reasonably assured to it under the terms of this Guarantee.

         SECTION 3.2. Certain Rights of Guarantee Trustee. (a) Subject to the
provisions of Section 3.1:

                           (i) The 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;

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

                           (iii) Whenever, in the administration of this
                  Guarantee, the Guarantee Trustee shall deem it desirable that
                  a matter be proved or established before



                                       8
<PAGE>   13

                  taking, suffering or omitting any action hereunder, the
                  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 Guarantee Trustee shall have no duty to see
                  to any recording, filing or registration or any instrument (or
                  any rerecording, refiling or re-registration thereof);

                           (v) The Guarantee Trustee may consult with counsel,
                  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 Guarantee Trustee shall have the right at any
                  time to seek instructions concerning the administration of
                  this Guarantee from any court of competent jurisdiction;

                           (vi) The Guarantee Trustee shall be under no
                  obligation to exercise any of the rights or powers vested in
                  it by this Guarantee at the request or direction of any
                  Holder, unless such Holder shall have provided to the
                  Guarantee Trustee such security and indemnity, reasonably
                  satisfactory to the Guarantee Trustee, against the costs,
                  expenses (including attorneys' fees and expenses and the
                  expenses of the 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 Guarantee
                  Trustee; provided, that nothing contained in this Section
                  3.2(a)(vi) shall be taken to relieve the Guarantee Trustee,
                  upon the occurrence of a Guarantee Event of Default, of its
                  obligation to exercise the rights and powers vested in it by
                  this Guarantee;

                           (vii) The 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 Guarantee Trustee, in its discretion, may
                  make such further inquiry or investigation into such facts or
                  matters as it may see fit;

                           (viii) The 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 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;

                           (ix) Any action taken by the Guarantee Trustee or its
                  agents hereunder shall bind the Holders, and the signature of
                  the 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 Guarantee
                  Trustee to so act



                                       9
<PAGE>   14

                  or as to its compliance with any of the terms and provisions
                  of this Guarantee, both of which shall be conclusively
                  evidenced by the Guarantee Trustee's or its agent's taking
                  such action; and

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

                  (b) No provision of this Guarantee shall be deemed to impose
any duty or obligation on the 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 Guarantee Trustee
shall be unqualified or incompetent to act 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 Guarantee Trustee
shall be construed to be a duty.

         SECTION 3.3. Not Responsible for Recitals or Issuance of Guarantee. The
recitals contained in this Guarantee shall be taken as the statements of the
Guarantor, and the Guarantee Trustee does not assume any responsibility for
their correctness. The Guarantee Trustee makes no representations as to the
validity or sufficiency of this Guarantee.

                                   ARTICLE 4

                                GUARANTEE TRUSTEE

         SECTION 4.1. Guarantee Trustee; Eligibility.

                  (a) There shall be at all times a 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 other 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



                                       10
<PAGE>   15

                  combined capital and surplus as set forth in its most recent
                  report of condition so published.

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

                  (c) If the Guarantee Trustee has or shall acquire any
"conflicting interest" within the meaning of Section 310(b) of the Trust
Indenture Act, the 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 Guarantee Trustee.

                  (a) Subject to Section 4.2(b), unless a Guarantee Event of
Default shall have occurred and be continuing, the Guarantee Trustee may be
appointed or removed with or without cause at any time by the Guarantor.

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

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

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

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

                  (f) Upon termination of this Guarantee or removal or
resignation of the Guarantee Trustee (or Successor Guarantee Trustee, as the
case may be) pursuant to this Section 4.2, the Guarantor shall pay to the
Guarantee Trustee (or Successor Guarantee Trustee, as the case may be) all
amounts owing for fees and reimbursement of expenses which have accrued to the
date of such termination, removal or resignation.



                                       11
<PAGE>   16

                                    ARTICLE 5

                                    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 Trust), as and when due, regardless of any
defense, right of set-off or counterclaim that the Trust 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 Trust to pay such amounts to the Holders. Notwithstanding anything to the
contrary herein, the Guarantor retains all of its rights under the Indenture to
extend the interest payment period on the Debentures pursuant to Section 3.11
thereof and the Guarantor shall not be obligated hereunder to make any Guarantee
Payments during any Extension Period (as defined in the certificate evidencing
the Debentures) with respect to the Distributions (as defined in the
Declaration) on the Securities.

         SECTION 5.2. Waiver of Notice and Demand. The Guarantor hereby waives
notice of acceptance of this Guarantee and of any liability to which it applies
or may apply, presentment, demand for payment, any right to require a proceeding
first against the Trust or any other Person before proceeding 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. The obligations, covenants,
agreements and duties of the Guarantor under this Guarantee shall be absolute
and unconditional and shall remain in full force and effect until the entire
liquidation amount of all outstanding Securities shall have been paid and such
obligation shall in no way be affected or impaired by reason of the happening
from time to time of any event, including without limitation, the following,
whether or not with notice to, or the consent of, the Guarantor:

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

                  (b) The extension of time for the payment by the Trust of all
         or any portion of the Distributions, Redemption Price, Liquidation
         Distribution or any other sums payable under the terms of the
         Securities or the extension of time for the performance of any other
         obligation under, arising out of, or in connection with the 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
         Debentures);

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



                                       12
<PAGE>   17

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

                  (e) Any invalidity of, or defect or deficiency in, the
         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 Guarantee Trustee or the
Holders to give notice to, or obtain consent of the Guarantor or any other
Person with respect to the happening of any of the foregoing.

                  No setoff, counterclaim, reduction or diminution of any
obligation, or any defense of any kind or nature that the Guarantor has or may
have against any Holder shall be available hereunder to the Guarantor against
such Holder to reduce the payments to it under this Guarantee.

         SECTION 5.4. Rights of Holders.

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

                  (b) If the Guarantee Trustee fails to enforce this Guarantee,
then any Holder of Securities may, subject to the subordination provisions of
Section 6.2, institute a legal proceeding directly against the Guarantor to
enforce the Guarantee Trustee's rights under this Guarantee without first
instituting a legal proceeding against the Trust, the Guarantee Trustee or any
other person or entity. In addition, if the Guarantor has failed to make a
Guarantee Payment, a Holder of Securities may, subject to the subordination
provisions of Section 6.2, directly institute a proceeding against the Guarantor
for enforcement of the Guarantee for such payment to the Holder of the
Securities of the principal of or interest on the Debentures on or after the
respective due dates specified in the Debentures, and the amount of the payment
will be based on the Holder's pro rata share of the amount due and owing on all
of the Securities. The Guarantor hereby waives any right or remedy to require
that any action on this Guarantee be brought first against the Trust or any
other person or entity before proceeding directly against the Guarantor.

         SECTION 5.5. Guarantee of Payment. This Guarantee creates a guarantee
of payment and not of collection.


                                       13
<PAGE>   18

         SECTION 5.6. Subrogation. The Guarantor shall be subrogated to all (if
any) rights of the Holders of Securities against the Trust in respect of any
amounts paid to such Holders by the Guarantor under this 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 Guarantee, if at the
time of any such payment, any amounts are due and unpaid under this 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 Guarantee Trustee for the benefit of the Holders.

         SECTION 5.7. Independent Obligations. The Guarantor acknowledges that
its obligations hereunder are independent of the obligations of the Trust with
respect to the Securities, and that the Guarantor shall be liable as principal
and as debtor hereunder to make Guarantee Payments pursuant to the terms of this
Guarantee notwithstanding the occurrence of any event referred to in subsections
5.3(a) through 5.3(g), inclusive, hereof.

         SECTION 5.8. Waiver Under Indenture and Debentures. Any waiver by the
Holders of any rights under the Indenture or the Declaration shall constitute a
waiver of their rights hereunder to the full extent of such waiver.


                                   ARTICLE 6

                    LIMITATION OF TRANSACTIONS; SUBORDINATION

         SECTION 6.1. Limitation of Transactions. So long as any Securities
remain outstanding, if (i) there shall have occurred an event of default under
the Indenture with respect to the Debentures, (ii) there shall be a Guarantee
Event of Default or (iii) the Guarantor shall have given notice of its election
of an Extension Period as provided in the certificate evidencing the Debentures
and shall not have rescinded such notice, or such Extension Period or any
extension thereof shall be continuing, then the Guarantor shall not, and shall
not permit any subsidiary of the Guarantor to, (x) declare or pay any dividends
or distributions on, or redeem, purchase, acquire or make a liquidation payment
with respect to, any of the Guarantor's capital stock or (y) make any payment of
principal, interest or premium, if any, on or repay, repurchase or redeem any
debt securities of the Guarantor that rank on a parity with or junior in
interest to the Debentures or make any guarantee payments with respect to any
guarantee by the Guarantor of the debt securities of any subsidiary of the
Guarantor if such guarantee ranks on a parity with or junior in interest to the
Debentures (other than (a) repurchases, redemptions or other acquisitions of
shares of the Guarantor's capital stock in connection with any employment
contract, benefit plan or other similar arrangement with or for the benefit of
any one or more employees, officers, directors or consultants, in connection
with a dividend reinvestment or stockholder stock purchase plan or in connection
with the issuance of the Guarantor's capital stock (or securities convertible
into or exercisable for such capital stock) as consideration in an acquisition
transaction entered into prior to the applicable default, Guarantee Event of
Default or Extension Period, as the case may be, (b) as a result of an exchange
or conversion of any class or series of the Guarantor's capital stock (or any
capital stock of a subsidiary of the Guarantor) for any class or series of the
Guarantor's capital stock or of any class or series of the Guarantor's



                                       14
<PAGE>   19

indebtedness for any class or series of the Guarantor's capital stock, (c) the
purchase of fractional interests in shares of the Guarantor's capital stock
pursuant to the conversion or exchange provisions of such capital stock or the
security being converted or exchanged, (d) any declaration of a dividend in
connection with any shareholders' rights plan, or the issuance of rights, stock
or other property under any such plan in the future, or the redemption or
repurchase of rights pursuant thereto, (e) payments under this Guarantee with
respect to the Securities, or (f) any dividend in the form of stock, warrants,
options or other rights where the dividend stock or the stock issuable upon
exercise of such warrants, options or other rights is the same stock as that on
which the dividend is being paid or ranks pari passu with or junior to such
stock).

         SECTION 6.2. Ranking. This Guarantee will constitute an unsecured
obligation of the Guarantor and will rank subordinate and junior in right of
payment to all Senior Debt (as defined in the Indenture) of the Guarantor in the
same manner and to the same extent as set forth in Article XIII of the
Indenture.

         SECTION 6.3. Subordination of Common Securities. If a Trust Enforcement
Event has occurred and is continuing under the Declaration, the rights of the
holders of the Common Securities to receive Guarantee Payments hereunder shall
be subordinated to the rights of the Holders of the Preferred Securities to
receive Guarantee Payments under this Guarantee.

                                    ARTICLE 7

                                   TERMINATION

                  This Guarantee shall terminate upon (i) full payment of the
Redemption Price of all Securities, (ii) distribution of the Debentures to the
Holders of all the Securities or (iii) full payment of the amounts payable in
accordance with the Declaration upon liquidation of the Trust. Notwithstanding
the foregoing, this Guarantee will continue to be effective or will be
reinstated, as the case may be, if at any time any Holder of Securities must
restore payment of any sums paid under the Securities or under this Guarantee.

                                    ARTICLE 8

                                 INDEMNIFICATION

         SECTION 8.1. Exculpation. 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 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 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.

                  (a) 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



                                       15
<PAGE>   20

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 of
Securities 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 Guarantee or the resignation
or removal of the Guarantee Trustee.

                                    ARTICLE 9

                                  MISCELLANEOUS

         SECTION 9.1. Successors and Assigns. All guarantees and agreements
contained in this Guarantee shall bind the successors, assigns, receivers,
trustees and representatives of the Guarantor and shall inure to the benefit of
the Holders of the Securities then outstanding.

         SECTION 9.2. Amendments. Except with respect to any changes that do not
materially adversely affect the rights of the Holders (in which case no consent
of the Holders will be required), this Guarantee may not be amended without the
prior approval of the Holders of at least a Majority in Liquidation Amount of
the Securities. The provisions of Section 11.2 of the Declaration with respect
to meetings of, and action by written consent of, the Holders of the Securities
apply to the giving of such approval.

         SECTION 9.3. Notices. All notices provided for in this Guarantee shall
be in writing, duly signed by the party giving such notice, and shall be
delivered by hand, telecopied or mailed by registered or certified mail, as
follows:

                  (a) If given to the Guarantee Trustee, at its Corporate Trust
         Office (or such other address as the Guarantee Trustee may give notice
         of to the Guarantor and the Holders of the Securities).

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


                           Comerica Incorporated
                           Comerica Tower at Detroit Center
                           Detroit, Michigan 48226
                           Attn: Mark W. Yonkman, MC 3391




                                       16
<PAGE>   21

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

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

         SECTION 9.5. Governing Law. THIS GUARANTEE SHALL BE GOVERNED BY AND
CONSTRUED AND INTERPRETED IN ACCORDANCE WITH THE LAW OF THE STATE OF NEW YORK.




  [The rest of this page has been left blank intentionally; the signature page
                                   follows.]





                                       17
<PAGE>   22


                  IN WITNESS WHEREOF, this Guarantee is executed as of the day
and year first above written.

                                   COMERICA INCORPORATED,
                                     as Guarantor


                                   By:
                                       -----------------------------------------
                                         Name:  Mark W. Yonkman
                                         Title: First Vice President, Assistant
                                                Secretary and General Counsel --
                                                Investment Bank & Corporate
                                                Finance



                                   CHASE MANHATTAN TRUST COMPANY,
                                   NATIONAL ASSOCIATION
                                     as Guarantee Trustee



                                   By:
                                       -----------------------------------------
                                         Name:  D. Kovach
                                         Title: Assistant Vice President



                                       18