Document:

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                                                                     EXHIBIT 4.3
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                            VALERO ENERGY CORPORATION

                               GUARANTEE AGREEMENT

                                   VEC TRUST I

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                            Dated as of June 28, 2000

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                                TABLE OF CONTENTS
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                                                     ARTICLE I
                                                    DEFINITIONS

SECTION 1.01      Definitions.....................................................................................1

                                                     ARTICLE II
                                                TRUST INDENTURE ACT

SECTION 2.01      Trust Indenture Act; Application................................................................5
SECTION 2.02      Lists of Holders of Preferred Securities........................................................5
SECTION 2.03      Reports by the Guarantee Trustee................................................................6
SECTION 2.04      Periodic Reports to the Guarantee Trustee.......................................................6
SECTION 2.05      Evidence of Compliance with Conditions Precedent................................................6
SECTION 2.06      Events of Default; Waiver.......................................................................7
SECTION 2.07      Disclosure of Information.......................................................................7
SECTION 2.08      Conflicting Interest............................................................................7

                                                     ARTICLE III
                                 POWERS, DUTIES AND RIGHTS OF THE GUARANTEE TRUSTEE

SECTION 3.01      Powers and Duties of the Guarantee Trustee......................................................7
SECTION 3.02      Certain Rights and Duties of the Guarantee Trustee..............................................8
SECTION 3.03      Not Responsible for Recitals or Issuance of Guarantee..........................................10
SECTION 3.04      The Guarantee Trustee May Own Preferred Securities.............................................11
SECTION 3.05      Moneys Received by the Guarantee Trustee to Be Held in Trust Without Interest..................11
SECTION 3.06      Compensation and Expenses of Guarantee Trustee.................................................11

                                                     ARTICLE IV
                                                 GUARANTEE TRUSTEE

SECTION 4.01      Qualifications.................................................................................12
SECTION 4.02      Appointment, Removal and Resignation of the Guarantee Trustee..................................12

                                                      ARTICLE V
                                                      GUARANTEE

SECTION 5.01      Guarantee......................................................................................13
SECTION 5.02      Waiver of Notice...............................................................................13
SECTION 5.03      Obligations Not Affected.......................................................................13
SECTION 5.04      Enforcement of Guarantee.......................................................................14
SECTION 5.05      Guarantee of Payment...........................................................................15
SECTION 5.06      Subrogation....................................................................................15
SECTION 5.07      Independent Obligations........................................................................15
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                                                     ARTICLE VI
                                     LIMITATION OF TRANSACTIONS; SUBORDINATION

SECTION 6.01      Limitation of Transactions.....................................................................16
SECTION 6.02      Subordination..................................................................................16

                                                     ARTICLE VII
                                                    TERMINATION

SECTION 7.01      Termination....................................................................................17

                                                    ARTICLE VIII
                                      LIMITATION OF LIABILITY; INDEMNIFICATION

SECTION 8.01      Exculpation....................................................................................17
SECTION 8.02      Indemnification................................................................................17
SECTION 8.03      Survive Termination............................................................................18

                                                     ARTICLE IX
                                                   MISCELLANEOUS

SECTION 9.01      Successors and Assigns.........................................................................18
SECTION 9.02      Amendments.....................................................................................18
SECTION 9.03      Notices........................................................................................18
SECTION 9.04      Genders........................................................................................19
SECTION 9.05      Benefit........................................................................................19
SECTION 9.06      Governing Law..................................................................................20
SECTION 9.07      Counterparts...................................................................................20
SECTION 9.08      Exercise of Overallotment Option...............................................................20
SECTION 9.09      Limited Liability..............................................................................20
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                               GUARANTEE AGREEMENT

         This GUARANTEE AGREEMENT, dated as of June 28, 2000, is executed and
delivered by Valero Energy Corporation, a Delaware corporation (the
"Guarantor"), and The Bank of New York, a national banking association, as the
initial Guarantee Trustee (as defined herein) for the benefit of the Holders (as
defined herein) from time to time of the Preferred Securities (as defined
herein) of VEC Trust I, a Delaware statutory business trust (the "Issuer").

         WHEREAS, pursuant to an Amended and Restated Declaration of Trust (the
"Declaration"), dated as of June 28, 2000 among the trustees of the Issuer named
therein, Valero Energy Corporation, as Sponsor, and the Holders from time to
time of preferred undivided beneficial interests in the assets of the Issuer,
the Issuer may issue up to $172,500,000 aggregate liquidation amount of its 7
3/4% Trust Preferred Securities (the "Preferred Securities") representing
preferred undivided beneficial interests in the assets of the Issuer and having
the terms set forth in the Declaration, of which $150,000,000 liquidation amount
of Preferred Securities is being issued as of the date hereof. Up to the
remaining $22,500,000 liquidation amount of Preferred Securities may be issued
by the Issuer if and to the extent that the over-allotment option granted by the
Guarantor and the Issuer pursuant to the Underwriting Agreement (as defined in
the Declaration) is exercised by the Underwriters named in the Underwriting
Agreement; and

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

         NOW, THEREFORE, in consideration of the purchase by the initial
purchasers thereof of Preferred Securities, which purchase the Guarantor hereby
agrees shall benefit the Guarantor, the Guarantor executes and delivers this
Guarantee Agreement for the benefit of the Holders from time to time.

                                    ARTICLE I
                                   DEFINITIONS

     SECTION 1.01 Definitions.

         (a) Capitalized terms used in this Guarantee Agreement but not defined
in the preamble or recitals above have the respective meanings assigned to them
in this Section 1.01.

         (b) A term defined anywhere in this Guarantee Agreement has the same
meaning throughout.

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         (c) All references to "the Guarantee Agreement" or "this Guarantee
Agreement" are to this Guarantee Agreement as modified, supplemented or amended
from time to time.

         (d) All references in this Guarantee Agreement to Articles and Sections
are to Articles and Sections of this Guarantee Agreement unless otherwise
specified.

         (e) A term defined in the Trust Indenture Act has the same meaning when
used in this Guarantee Agreement unless otherwise defined in this Guarantee
Agreement or unless the context otherwise requires.

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

         "Additional Amounts" has the meaning set forth in the Indenture.

         "Affiliate" of any specified Person means any other Person directly or
indirectly controlling or controlled by, or under direct or indirect common
control with, such specified Person. For purposes of this definition, "control"
of a Person shall mean the power to direct the management and policies of such
Person, directly or indirectly, whether through the ownership of voting
securities, by contract or otherwise, and the terms "controlling" and
"controlled" shall have meanings correlative to the foregoing.

         "Business Day" has the meaning set forth in the Indenture.

         "Commission" means the Securities and Exchange Commission.

         "Common Securities" means the securities representing common undivided
beneficial interests in the assets of the Issuer and having the terms set forth
in Article VII of the Declaration.

         "Common Stock" means the common stock, $.01 par value per share, of the
Guarantor, including associated preferred share purchase rights.

         "Declaration" has the meaning set forth in the recitals above.

         "Distributions" means the periodic distributions and other payments
payable to Holders in accordance with the terms of the Preferred Securities set
forth in Article VII of to the Declaration.

         "Dollar" has the meaning set forth in the Indenture.

         "Event of Default" means a default by the Guarantor on any of its
payment or other obligations under this Guarantee Agreement; provided, however,
that, except with respect to a default in payment of any Guarantee Payment, any
such default shall constitute an Event of Default

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only if the Guarantor shall have received notice of such default and shall not
have cured such default within 60 days after receipt of such notice.

         "Extension Period" has the meaning set forth in Section 2.8 of the
Supplemental Indenture.

         "Guarantee Payments" means the following payments or distributions,
without duplication, with respect to the Preferred Securities, to the extent not
paid or made by or on behalf of the Issuer: (i) any accumulated and unpaid
Distributions, any Additional Amounts payable with respect to the Preferred
Securities in accordance with the terms thereof and the Redemption Price,
including all accumulated and unpaid Distributions and Additional Amounts to the
date of redemption, with respect to the Preferred Securities called for
redemption by the Issuer but only if and to the extent that in each case the
Guarantor has made a payment to the Property Trustee of principal of, any
premium or interest on or any Additional Amounts with respect to the Notes and
(ii) upon a voluntary or involuntary dissolution, winding-up or termination of
the Issuer (other than in connection with the distribution of Notes to Holders
in exchange for Preferred Securities or the redemption of the Preferred
Securities in full upon the maturity or redemption of the Notes as provided in
the Declaration), the lesser of (a) the aggregate of the liquidation amount and
all accumulated and unpaid Distributions and Additional Amounts on the Preferred
Securities to the date of payment, to the extent the Issuer has funds on hand
legally available therefor, and (b) the amount of assets of the Issuer remaining
available for distribution to Holders in liquidation of the Issuer as required
by applicable law.

         "Guarantee Trustee" means The Bank of New York, a New York banking
corporation, until a Successor Guarantee Trustee has been appointed and has
accepted such appointment pursuant to the terms of this Guarantee Agreement, and
thereafter means each such Successor Guarantee Trustee.

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

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

         "Indenture" means the Indenture dated as of December 12, 1997 between
the Guarantor and The Bank of New York, as trustee, as supplemented by the First
Supplemental Indenture thereto dated as of June 28, 2000 (the "Supplemental
Indenture"), pursuant to which the Notes are to be issued to the Property
Trustee.

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         "Majority of Outstanding Preferred Securities" means Holder(s) of
outstanding Preferred Securities, voting together as a single class, who are the
record owners of Preferred Securities representing more than 50% of the
outstanding Preferred Securities.

         "Notes" means the series of unsecured senior notes issued to the
Property Trustee by the Guarantor under the Indenture and entitled the "7 3/4%
Senior Deferrable Notes due 2005."

         "Officers' Certificate" means, with respect to any Person, a
certificate signed by the Chairman of the Board, the President, any Vice
Chairman of the Board, any Vice President, the Chief Financial Officer, the
Treasurer, any Assistant Treasurer, the Controller, the Secretary or any
Assistant Secretary of such Person, and delivered to the Guarantee Trustee. One
of the officers signing an Officers' Certificate given pursuant to Section 2.04
shall be the principal executive, financial or accounting officer of the
Guarantor. Any Officers' Certificate delivered with respect to compliance with a
condition or covenant provided for in this Guarantee Agreement shall include:

         (i) a statement that the person making such certificate has read such
     covenant or condition;

         (ii) a brief statement as to the nature and scope of the examination
     or investigation upon which the statements or opinions contained in such
     certificate are based;

         (iii) a statement that, in the opinion of such person, he has made
     such examination or investigation as is necessary to enable him 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 or not, in the opinion of such person,
     such condition or covenant has been complied with.

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

         "Preferred Securities" has the meaning set forth in the recitals above.

         "Property Trustee" means the Person acting as Property Trustee under
the Declaration.

         "Redemption Price" means the amount payable on redemption of the
Preferred Securities in accordance with the terms of the Preferred Securities.

         "Responsible Officer" means, when used with respect to the Guarantee
Trustee, any officer within the corporate trust department of the Guarantee
Trustee, including any vice president,

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assistant vice president, assistant secretary, assistant treasurer, trust
officer or any other officer of the Guarantee Trustee who customarily performs
functions similar to those performed by the Persons who at the time shall be
such officers, respectively, or to whom any corporate trust matter is referred
because of such Person's knowledge of and familiarity with the particular
subject and, in either case, who shall have direct responsibility for the
administration of this Guarantee Agreement.

         "Successor Guarantee Trustee" means a successor Guarantee Trustee
possessing the qualifications to act as a Guarantee Trustee under Section 4.01.

         "Supplemental Indenture" has the meaning specified in the definition of
Indenture.

         "Trust Enforcement Event" has the meaning specified in the Declaration.

         "Trust Indenture Act" means the Trust Indenture Act of 1939, as
amended.

                                   ARTICLE II
                               TRUST INDENTURE ACT

     SECTION 2.01 Trust Indenture Act; Application.

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

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

         (c) The application of the Trust Indenture Act to this Guarantee
Agreement shall not affect the nature of the Preferred Securities as equity
securities representing preferred undivided beneficial interests in the assets
of the Issuer.

     SECTION 2.02 Lists of Holders of Preferred Securities.

         (a) The Guarantor shall provide the Guarantee Trustee (unless the
Guarantee Trustee is the registrar of the Preferred Securities) (i) within 14
days after each record 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 ("List of Holders") as of such date, and (ii) at any other time,
within 30 days of receipt by the Guarantor of a written request for a List of
Holders as of a date no more than 15 days before such List of Holders is given
to the Guarantee Trustee; provided that in each case the Guarantor shall not be
obligated to provide such List of Holders at any time that the List of Holders
does not differ from the most recent List of Holders given to the Guarantee
Trustee

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by the Guarantor. The Guarantee Trustee shall preserve, in as current a form as
is reasonably practicable, all information contained in the 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
Section 312(b) of the Trust Indenture Act.

     SECTION 2.03 Reports by the Guarantee Trustee.

         Within 60 days after June 15th of each year, commencing June 15, 2001,
the Guarantee Trustee shall deliver to the Holders such reports as are required
by Section 313 of the Trust Indenture Act, if any, in the form, in the manner
and at the times provided by Section 313 of the Trust Indenture Act. The
Guarantee Trustee shall also comply with the other requirements of Section 313
of the Trust Indenture Act. A copy of each such report shall, at the time of
such transmission to the Holders, be filed by the Guarantee Trustee with the
Guarantor, with each stock exchange or quotation system upon which any Preferred
Securities are listed or traded (if so listed or traded) and also with the
Commission. The Guarantor agrees to notify the Guarantee Trustee when any
Preferred Securities become listed on any stock exchange or quotation system and
of any delisting thereof.

     SECTION 2.04 Periodic Reports to the Guarantee Trustee.

         The Guarantor shall provide to the Guarantee Trustee, the Commission
and the Holders, as applicable, such documents, reports and information (if any)
as required by Section 314(a)(1)-(3) of the Trust Indenture Act and the
compliance certificates required by Section 314(a)(4) and (c) of the Trust
Indenture Act, any such certificates to be provided in the form, in the manner
and at the times required by Section 314(a)(4) and (c) of the Trust Indenture
Act (provided that any certificate to be provided pursuant to Section 314(a)(4)
of the Trust Indenture Act shall be provided within 120 days of the end of each
fiscal year of the Issuer). Delivery of such reports, information and documents
to the Guarantee Trustee is for informational purposes only and the Guarantee
Trustee's receipt of such shall not constitute constructive notice of any
information contained therein, including the Guarantor's compliance with any of
its covenants hereunder (as to which the Guarantee Trustee is entitled to rely
exclusively on Officers' Certificates or on certificates provided pursuant to
this Section 2.04).

     SECTION 2.05 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
Agreement which 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) may be given in the form of an Officers'
Certificate.

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     SECTION 2.06 Events of Default; Waiver.

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

         (b) The right of any Holder to receive payment of the Guarantee
Payments in accordance with this Guarantee Agreement, or to institute suit for
the enforcement of any such payment, shall not be impaired without the consent
of each such Holder.

     SECTION 2.07 Disclosure of Information.

         The disclosure of information as to the names and addresses of the
Holders 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 2.08 Conflicting Interest.

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

         (b) The Guarantee Trustee shall comply with its obligations under
Sections 310(b) and 311 of the Trust Indenture Act.

                                   ARTICLE III
               POWERS, DUTIES AND RIGHTS OF THE GUARANTEE TRUSTEE

     SECTION 3.01 Powers and Duties of the Guarantee Trustee.

         (a) This Guarantee Agreement shall be held by the Guarantee Trustee in
trust for the benefit of the Holders. The Guarantee Trustee shall not transfer
its right, title and interest in this Guarantee Agreement to any Person except a
Successor Guarantee Trustee on acceptance by such Successor Guarantee Trustee of
its appointment to act as Guarantee Trustee or to a Holder exercising his or her
rights pursuant to Section 5.04(iv). The right, title and interest of the
Guarantee Trustee to this Guarantee Agreement shall vest automatically in each
Person who may hereafter be appointed

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as Guarantee Trustee in accordance with Article IV. Such vesting and cessation
of title shall be effective whether or not conveyancing documents have been
executed and delivered.

         (b) If an Event of Default has occurred and is continuing, the
Guarantee Trustee shall enforce this Guarantee Agreement for the benefit of the
Holders.

         (c) This Guarantee Agreement and all moneys received by the Guarantee
Trustee in respect of the Guarantee Payments will not be subject to any right,
charge, security interest, lien or claim of any kind in favor of, or for the
benefit of, the Guarantee Trustee or its agents or their creditors.

         (d) The Guarantee Trustee shall, within 90 days after the occurrence of
an Event of Default actually known to a Responsible Officer of the Guarantee
Trustee, transmit by mail, first class postage prepaid, to the Holders, as their
names and addresses appear upon the List of Holders, notice of all such Events
of Default, unless such defaults shall 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 the board of directors, the executive committee or
a trust committee of directors and/or Responsible Officers of the Guarantee
Trustee in good faith determines that the withholding of such notice is in the
interests of the Holders. The Guarantee Trustee shall not be deemed to have
knowledge of any Event of Default except any Event of Default as to which the
Guarantee Trustee shall have received written notice or a Responsible Officer
charged with the administration of this Guarantee Agreement shall have obtained
written notice of such Event of Default.

         (e) The Guarantee Trustee shall continue to serve as a trustee until a
Successor Guarantee Trustee has been appointed and accepted that appointment in
accordance with Article IV.

     SECTION 3.02 Certain Rights and Duties of the Guarantee Trustee.

         (a) The Guarantee Trustee, before the occurrence of an Event of Default
and after the curing or waiving of all Events of Default that may have occurred,
shall undertake to perform only such duties as are specifically set forth in
this Guarantee Agreement, and no implied covenants shall be read into this
Guarantee Agreement against the Guarantee Trustee. In case an Event of Default
has occurred (that has not been cured or waived pursuant to Section 2.06), the
Guarantee Trustee shall exercise such of the rights and powers vested in it by
this Guarantee Agreement, 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 own affairs.

         (b) No provision of this Guarantee Agreement 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 an Event of Default and after the
     curing or waiving of all such Events of Default that may have occurred:

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               (A) the duties and obligations of the Guarantee Trustee shall be
          determined solely by the express provisions of this Guarantee
          Agreement, 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 Agreement, and no implied covenants or
          obligations shall be read into this Guarantee Agreement against the
          Guarantee Trustee; and

               (B) in the absence of willful misconduct on the part of the
          Guarantee Trustee, the Guarantee Trustee may conclusively rely, as to
          the truth of the statements and the correctness of the opinions
          expressed therein, upon any certificates or opinions furnished to the
          Guarantee Trustee and conforming to the requirements of this Guarantee
          Agreement; provided, however, that in the case of any such
          certificates or opinions that by any provision hereof or the Trust
          Indenture Act 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 Agreement or the Trust Indenture Act,
          as the case may be (but need not confirm or investigate the accuracy
          of mathematical calculations or other facts stated therein);

          (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 a Majority of Outstanding Preferred
     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 Agreement; and

          (iv) no provision of this Guarantee Agreement 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 it 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 Agreement or
     indemnity reasonably satisfactory to it against such risk or liability is
     not reasonably assured to it.

     (c) Subject to the provisions of Section 3.02(a) and (b):

          (i) whenever in the administration of this Guarantee Agreement, the
     Guarantee Trustee shall deem it desirable that a matter be proved or
     established prior to taking, suffering or omitting any action hereunder,
     the Guarantee Trustee (unless other evidence is

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     herein specifically prescribed) may, in the absence of willful misconduct
     on its part, request and rely upon an Officers' Certificate, which, upon
     receipt of such request, shall be promptly delivered by the Guarantor;

          (ii) the Guarantee Trustee (A) may consult with counsel (which may be
     counsel to the Guarantor or any of its Affiliates and may include any of
     its employees) selected by it in good faith and with due care 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 reliance
     thereon and in accordance with such advice and opinion and (B) shall have
     the right at any time to seek, at the expense of the Guarantor,
     instructions concerning the administration of this Guarantee Agreement from
     any court of competent jurisdiction;

          (iii) the Guarantee Trustee may execute any of the trusts or powers
     hereunder or perform any duties hereunder either directly or by or through
     agents or attorneys, and the Guarantee Trustee shall not be responsible for
     any willful misconduct or negligence on the part of any agent or attorney
     appointed by it in good faith and with due care;

          (iv) the Guarantee Trustee shall be under no obligation to exercise
     any of the rights or powers vested in it by this Guarantee Agreement at the
     request or direction of any Holder, unless such Holder shall have offered
     to the Guarantee Trustee security and indemnity satisfactory to the
     Guarantee Trustee against the costs, expenses (including attorneys' fees
     and expenses) and liabilities that might be incurred by it in complying
     with such request or direction; provided that nothing contained in this
     clause (iv) shall relieve the Guarantee Trustee of the obligation, upon the
     occurrence of an Event of Default (which has not been cured or waived) to
     exercise such of the rights and powers vested in it by this Guarantee
     Agreement, and to use the same degree of care and skill in this exercise as
     a prudent person would exercise or use under the circumstances in the
     conduct of his own affairs; and

          (v) 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;
     and no third party shall be required to inquire as to the authority of the
     Guarantee Trustee to so act, or as to its compliance with any of the terms
     and provisions of this Guarantee Agreement, both of which shall be
     conclusively evidenced by the Guarantee Trustee's or its agent's taking
     such action.

     SECTION 3.03 Not Responsible for Recitals or Issuance of Guarantee.

         The recitals contained in this Guarantee Agreement 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 Agreement.

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     SECTION 3.04 The Guarantee Trustee May Own Preferred Securities.

         The Guarantee Trustee, in its individual or any other capacity, may
become the owner or pledgee of Preferred Securities and may otherwise deal with
the Guarantor with the same rights it would have if it were not the Guarantee
Trustee.

     SECTION 3.05 Moneys Received by the Guarantee Trustee to Be Held in Trust
Without Interest.

         All moneys received by the Guarantee Trustee in respect of Guarantee
Payments shall, until used or applied as herein provided, be held in trust for
the purposes for which they were received, but need not be segregated from other
funds except to the extent required by law. The Guarantee Trustee shall be under
no liability for interest on any moneys received by it hereunder except such as
it may agree in writing to pay thereon.

     SECTION 3.06 Compensation and Expenses of Guarantee Trustee.

         The Guarantor covenants and agrees to pay to the Guarantee Trustee from
time to time, and the Guarantee Trustee shall be entitled to, such compensation
as the Guarantor and the Guarantee Trustee shall from time to time agree in
writing (which shall not be limited by any provision of law in regard to the
compensation of a Guarantee Trustee of an express trust) for all services
rendered by it in the exercise and performance of any of the powers and duties
hereunder of the Guarantee Trustee, and the Guarantor will pay or reimburse the
Guarantee Trustee upon its request for all reasonable expenses, disbursements
and advances incurred or made by the Guarantee Trustee in accordance with any of
the provisions of this Guarantee Agreement (including the reasonable
compensation and the reasonable expenses and disbursements of its counsel and of
all persons not regularly in its employ) except any such expense, disbursement
or advance as may arise from its negligence or willful misconduct. The Guarantor
also covenants to indemnify each of the Guarantee Trustee or any predecessor
Guarantee Trustee and their officers, agents, directors and employees for, and
to hold them harmless against, any and all loss, liability, damage, claim or
expense including taxes (other than taxes based upon, measured by or determined
by the income, profit, franchise or doing business of the Guarantee Trustee)
incurred without negligence or willful misconduct on the part of the Guarantee
Trustee and arising out of or in connection with the acceptance or
administration of this trust, including the reasonable costs and expenses of
defending itself against any claim (whether asserted by the Guarantor, any
Holder or any other Person) of liability in the premises. The provisions of this
Section 3.06 shall survive the termination of this Guarantee Agreement and
resignation or removal of the Guarantee Trustee.

                                       11

<PAGE>   15

                                   ARTICLE IV
                                GUARANTEE TRUSTEE

     SECTION 4.01 Qualifications.

          There shall at all times be a Guarantee Trustee that shall:

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

          (ii) be a national banking association or corporation organized and
     doing business under the laws of the United States of America or any State
     or Territory thereof or of the District of Columbia, or a corporation or
     Person permitted by the 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
     $50,000,000, 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 clause (ii), the combined capital and surplus
     of such corporation shall be deemed to be its combined capital and surplus
     as set forth in its most recent report of condition so published.

         If at any time the Guarantee Trustee shall cease to satisfy the
requirements of clauses (i) and (ii) above, the Guarantee Trustee shall
immediately resign in the manner and with the effect set out in Section 4.02. 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
the Guarantor shall in all respects comply with the provisions of Section 310(b)
of the Trust Indenture Act.

     SECTION 4.02 Appointment, Removal and Resignation of the Guarantee Trustee.

         (a) Subject to Section 4.02(b), the Guarantee Trustee may be appointed
or removed without cause at any time by the Guarantor.

         (b) The Guarantee Trustee shall not be removed in accordance with
Section 4.02(a) until a Successor Guarantee Trustee possessing the
qualifications to act as Guarantee Trustee under Section 4.01 has been appointed
and has accepted such appointment by written instrument executed by such
Successor Guarantee Trustee and delivered to the Guarantor and the Guarantee
Trustee being removed.

         (c) The Guarantee Trustee appointed to office shall hold office until
its successor shall have been appointed or until its removal or resignation.

         (d) The Guarantee Trustee may resign from office (without need for
prior or subsequent accounting) by an instrument (a "Resignation Request") in
writing signed by the

                                       12

<PAGE>   16

Guarantee Trustee and delivered to the Guarantor, which resignation shall take
effect upon such delivery or upon such later date as is specified therein;
provided, however, that no such resignation of the Guarantee Trustee shall be
effective until a Successor Guarantee Trustee possessing the qualifications to
act as Guarantee Trustee under Section 4.01 has been appointed and has accepted
such appointment by instrument executed by such Successor Guarantee Trustee and
delivered to the Guarantor and the resigning Guarantee Trustee.

         (e) If no Successor Guarantee Trustee shall have been appointed and
accepted appointment as provided in this Section 4.02 within 60 days after
delivery to the Guarantor of a Resignation Request or receipt of a notice of
removal by the Guarantee Trustee, the Guarantee Trustee resigning or to be
removed may, at the expense of the Guarantor petition any court of competent
jurisdiction for appointment of a Successor Guarantee Trustee. Such court may
thereupon after such notice, if any, as it may deem proper, appoint a Successor
Guarantee Trustee.

                                    ARTICLE V
                                    GUARANTEE

     SECTION 5.01 Guarantee.

         The Guarantor irrevocably and unconditionally agrees to pay in full to
the Holders the Guarantee Payments (without duplication of amounts theretofore
paid by the Issuer), as and when due, regardless of any defense, right of
set-off or counterclaim which the Issuer may have or assert. The Guarantor's
obligation to make a Guarantee Payment may be satisfied by direct payment of the
required amounts by the Guarantor to the Holders or to the Guarantee Trustee for
remittance to the Holders or by causing the Issuer to pay such amounts to the
Holders.

     SECTION 5.02 Waiver of Notice.

         The Guarantor hereby waives notice of acceptance of this Guarantee
Agreement and of any liability to which it applies or may apply, presentment,
demand for payment, any right to require a proceeding first against the Issuer
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. Notwithstanding anything to the contrary herein, the Guarantor retains
all of its rights under the Indenture to extend the interest payment period on
the Notes and the Guarantor shall not be obligated hereunder to make any
Guarantee Payment during any Extension Period with respect to the Distributions
on the Preferred Securities.

     SECTION 5.03 Obligations Not Affected.

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

                                       13

<PAGE>   17

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

          (b) the extension of time for the payment by the Issuer of all or any
     portion of the Distributions (other than an extension of time for payment
     of Distributions that result from any Extension Period), Redemption Price,
     Liquidation Distribution (as defined in the Declaration) or any other sums
     payable under the terms of the Preferred Securities or the extension of
     time for the performance of any other obligation under, arising out of, or
     in connection with, the Preferred Securities (other than an extension of
     time for payment of Distributions that result from any Extension Period);

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

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

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

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

          (g) any other circumstance whatsoever that might otherwise constitute
     a legal or equitable discharge or defense of a guarantor, it being the
     intent of this Section 5.03 that the obligations of the Guarantor with
     respect to the Guarantee Payments 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 with respect to the
happening of any of the foregoing.

     SECTION 5.04 Enforcement of Guarantee.

         The Guarantor and the Guarantee Trustee expressly acknowledge and agree
that (i) this Guarantee Agreement will be deposited with the Guarantee Trustee
to be held for the benefit of the Holders; (ii) the Guarantee Trustee has the
right to enforce this Guarantee Agreement on behalf of the Holders; (iii)
Holders representing not less than a Majority of Outstanding Preferred
Securities have the right to direct the time, method and place of conducting any
proceeding for any

                                       14

<PAGE>   18

remedy available to the Guarantee Trustee in respect of this Guarantee Agreement
or exercising any trust or other power conferred upon the Guarantee Trustee
under this Guarantee Agreement; and (iv) if the Guarantee Trustee fails to
enforce this Guarantee Agreement as provided in clauses (ii) and (iii) above,
any Holder may institute a legal proceeding directly against the Guarantor to
enforce its rights under this Guarantee Agreement, without first instituting a
legal proceeding against the Issuer, the Guarantee Trustee or any other Person.
Notwithstanding the foregoing, if the Guarantor has failed to make a Guarantee
Payment, a Holder may directly institute a proceeding against the Guarantor for
enforcement of this Guarantee Agreement for such payment without first
instituting a legal proceeding against the Issuer, the Guarantee Trustee or any
other Person.

     SECTION 5.05 Guarantee of Payment.

         This Guarantee Agreement creates a guarantee of payment and not merely
of collection. This Guarantee Agreement will not be discharged except by payment
of the Guarantee Payments in full (without duplication of amounts theretofore
paid by the Issuer) or upon the distribution of the Notes to the Holders as
provided in the Declaration.

     SECTION 5.06 Subrogation.

         The Guarantor shall be subrogated to all (if any) rights of the Holders
against the Issuer in respect of any amounts paid to the Holders by the
Guarantor under this Guarantee Agreement; provided, however, that the Guarantor
shall not (except to the extent required by mandatory provisions of law) be
entitled to enforce or exercise any rights which 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 Agreement, if, at the time of any such
payment, any amounts are due and unpaid under this Guarantee Agreement. If any
amount shall be paid to the Guarantor in violation of the preceding sentence,
the Guarantor agrees to hold such amount in trust for the Holders and to pay
over such amount to the Holders or to the Guarantee Trustee for remittance to
the Holders.

     SECTION 5.07 Independent Obligations.

         The Guarantor acknowledges that its obligations hereunder are
independent of the obligations of the Issuer with respect to the Preferred
Securities and that the Guarantor shall be liable as principal and as debtor
hereunder to make Guarantee Payments pursuant to the terms of this Guarantee
Agreement notwithstanding the occurrence of any event referred to in subsections
(a) through (g), inclusive, of Section 5.03 hereof.

                                       15

<PAGE>   19

                                   ARTICLE VI
                    LIMITATION OF TRANSACTIONS; SUBORDINATION

     SECTION 6.01 Limitation of Transactions.

         So long as any Preferred Securities remain outstanding, the Guarantor
shall not (a) make any payment of principal, interest or premium, if any, on or
repay, repurchase or redeem any debt securities that rank junior to the Notes in
the right of payment issued by the Guarantor, or (b) make any guarantee payments
with respect to any guarantee by the Guarantor of any securities of any of its
subsidiaries if such guarantee ranks junior to the Notes in the right of payment
or (c) 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, except for or as a result of (i) dividends or distributions in,
or options, warrants or rights to subscribe for or purchase, the Guarantor's
common stock; (ii) any declaration of a dividend in connection with the
implementation of a shareholder's rights plan, or the issuance of shares under
any such plan in the future, or the redemption or repurchase of any such rights
pursuant thereto; (iii) a reclassification of the Guarantor's capital stock
solely into shares of one or more classes or series of the Guarantor's capital
stock or the exchange or conversion of one class or series of the Guarantor's
capital stock for or into another class or series of the Guarantor's capital
stock; (iv) 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; and (v) the purchase of the
Guarantor's common stock in connection with the Guarantor's normal course issuer
bid-purchases for the satisfaction by the Guarantor of its obligations under any
benefit plans for the Guarantor and the Guarantor's subsidiaries' directors,
officers or employees or under any of the Guarantor's dividend reinvestment
plans, if at such time (i) the Guarantor shall be in default with respect to its
Guarantee Payments or other payment obligations hereunder, (ii) there shall have
occurred and be continuing any event of default under the Declaration or (iii)
the Guarantor shall have given notice of its election of an Extension Period and
such period, or any extension thereof, is continuing. In addition, so long as
any Preferred Securities remain outstanding, the Guarantor (i) will remain the
sole direct or indirect owner of all of the outstanding Common Securities and
shall not cause or permit the Common Securities to be transferred except to the
extent such transfer is permitted under the Declaration; provided that any
permitted successor of the Guarantor under the Indenture may succeed to the
Guarantor's direct or indirect ownership of the Common Securities, (ii) will
cause the holder of the Common Securities to satisfy the requirements of Section
5.3 of the Declaration and (iii) will use reasonable efforts to cause the Issuer
to continue to be treated as a grantor trust for United States federal income
tax purposes, except in connection with a distribution of Notes as provided in
the Declaration.

     SECTION 6.02 Subordination.

         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 will be subordinated to the rights of the Holders of the
Preferred Securities to receive Guarantee Payments.

                                       16

<PAGE>   20

                                  ARTICLE VII
                                  TERMINATION

     SECTION 7.01 Termination.

         This Guarantee Agreement shall terminate and be of no further force and
effect (i) upon full payment of the Redemption Price of all Preferred
Securities, (ii) upon the distribution of Notes to Holders and holders of Common
Securities in exchange for all of the Preferred Securities and Common Securities
or (iii) upon full payment of the amounts payable in accordance with the
Declaration upon liquidation of the Issuer. Notwithstanding the foregoing, this
Guarantee Agreement will continue to be effective or will be reinstated, as the
case may be, if at any time any Holder must restore payment of any sums paid
with respect to the Preferred Securities or under this Guarantee Agreement.

                                  ARTICLE VIII
                    LIMITATION OF LIABILITY; INDEMNIFICATION

     SECTION 8.01 Exculpation.

         (a) No Indemnified Person shall be liable, responsible or accountable
in damages or otherwise to the Guarantor or any Holder for any loss, damage 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 Agreement and
in a manner such Indemnified Person reasonably believed to be within the scope
of the authority conferred on such Indemnified Person by this Guarantee
Agreement or by law, except that an Indemnified Person shall be liable for any
such loss, damage or claim incurred by reason of such Indemnified Person's
negligence or willful misconduct with respect to such acts or omissions.

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

     SECTION 8.02 Indemnification.

         To the fullest extent permitted by applicable law, the Guarantor shall
indemnify and hold harmless each Indemnified Person from and against any loss,
damage or claim incurred by such Indemnified Person by reason of any act or
omission performed or omitted by such Indemnified Person in good faith in
accordance with this Guarantee Agreement and in a manner such Indemnified

                                       17

<PAGE>   21
Person reasonably believed to be within the scope of authority conferred on
such Indemnified Person by this Guarantee Agreement, except that no Indemnified
Person shall be entitled to be indemnified in respect of any loss, damage or
claim incurred by such Indemnified Person by reason of negligence or willful
misconduct with respect to such acts or omissions.

     SECTION 8.03 Survive Termination.

         The provisions of Sections 8.01 and 8.02 shall survive the termination
of this Guarantee Agreement or the resignation or removal of the Guarantee
Trustee.

                                   ARTICLE IX
                                  MISCELLANEOUS

     SECTION 9.01 Successors and Assigns.

         All guarantees and agreements contained in this Guarantee Agreement
shall bind the successors, assignees, receivers, trustees and representatives of
the Guarantor and shall inure to the benefit of the Guarantee Trustee and the
Holders then outstanding. Except in connection with a consolidation, merger or
sale involving the Guarantor that is permitted under Article X of the Indenture,
the Guarantor shall not assign its obligations hereunder.

     SECTION 9.02 Amendments.

         Except with respect to any changes which do not adversely affect the
rights of Holders in any material respect (in which case no consent of Holders
will be required), this Guarantee Agreement may only be amended with the prior
approval of the Guarantor, the Guarantee Trustee and the Holders of not less
than a Majority of Outstanding Preferred Securities. The provisions of Section
11.2 of the Declaration concerning meetings of Holders shall apply to the giving
of such approval.

     SECTION 9.03 Notices.

         Any notice, request or other communication required or permitted to be
given hereunder shall be in writing, in English, duly signed by the party giving
such notice, and delivered, telecopied or mailed by first class mail as follows:

                                       18

<PAGE>   22

          (a) if given to the Guarantor, to the address set forth below or such
     other address as the Guarantor may give notice of to the Holders:

           Valero Energy Corporation
           One Valero Place
           P.O. Box 500
           San Antonio, Texas 78212
           Attention:  Jay D. Browning, Corporate Secretary
           Facsimile:  (210) 370-2988

     with a copy to:

           Attention:  Donna M. Titzman
           Facsimile:  (210) 370-2497

          (b) if given to the Guarantee Trustee, to the address set forth below
     or such other address as the Guarantee Trustee may give notice of to the
     Holders:

           The Bank of New York
           101 Barclay Street
           21 West
           New York, New York 10286
           Attention: Corporate Trust Trustee Administration
           Facsimile:  (212) 815-5915

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

         All notices hereunder shall be deemed to have been given when (i)
received in person, (ii) telecopied with receipt confirmed, or (iii) mailed by
first class mail, postage prepaid, when received, 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 9.04 Genders.

         The masculine, feminine and neuter genders used herein shall include
the masculine, feminine and neuter genders.

     SECTION 9.05 Benefit.

         This Guarantee Agreement is solely for the benefit of the Guarantee
Trustee and the Holders and, subject to Section 3.01(a), is not separately
transferable from the Preferred Securities.

                                       19

<PAGE>   23

     SECTION 9.06 Governing Law.

         THIS GUARANTEE AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED AND
INTERPRETED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK (WITHOUT REGARD
TO PRINCIPLES OF CONFLICTS OF LAWS).

     SECTION 9.07 Counterparts.

         This Guarantee Agreement may be executed in counterparts, each of which
shall be an original; but such counterparts shall together constitute one and
the same instrument.

     SECTION 9.08 Exercise of Overallotment Option.

         If and to the extent that Preferred Securities are issued by the Issuer
upon exercise of the overallotment option referred to in the first WHEREAS
clause, the Guarantor agrees to give prompt notice thereof to the Guarantee
Trustee but the failure to give such notice shall not relieve the Guarantor of
any of its obligations hereunder.

     SECTION 9.09 Limited Liability.

         Neither the Guarantee Trustee nor the Holders, in their capacities as
such, shall be personally liable for any liabilities or obligations of the
Guarantor arising out of this Guarantee Agreement. The parties further hereby
agree that the Holders, in their capacities as such, shall be entitled to the
same limitation of personal liability extended to the stockholders of private
corporations for profit organized under the General Corporation Law of the State
of Delaware.

                                       20

<PAGE>   24

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

                        VALERO ENERGY CORPORATION

                        By:
                            ------------------------------------------------
                            John D. Gibbons, Vice President
                            and Chief Financial Officer

                        THE BANK OF NEW YORK
                            as Guarantee Trustee

                        By:
                            ------------------------------------------------
                            Name:
                            Title:

                                       21<PAGE>   1

                                                                     EXHIBIT 4.4
================================================================================

                            VALERO ENERGY CORPORATION

                                       and

                              THE BANK OF NEW YORK,

                           as Purchase Contract Agent

                           PURCHASE CONTRACT AGREEMENT

                            Dated as of June 28, 2000

================================================================================

<PAGE>   2

                                TABLE OF CONTENTS

                                   ----------

<TABLE>
<CAPTION>
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                                                                                                               ----
<S>                                                                                                            <C>
ARTICLE 1
         DEFINITIONS AND OTHER PROVISIONS OF GENERAL APPLICATIONS
         SECTION 1.01.  Definitions...............................................................................1
         SECTION 1.02.  Compliance Certificates and Opinions.....................................................11
         SECTION 1.03.  Form of Documents Delivered to Purchase Contract Agent...................................11
         SECTION 1.04.  Acts of Holders; Record Dates............................................................12
         SECTION 1.05.  Notices..................................................................................13
         SECTION 1.06.  Notice to Holders; Waiver................................................................15
         SECTION 1.07.  Effect of Headings and Table of Contents.................................................15
         SECTION 1.08.  Successors and Assigns...................................................................15
         SECTION 1.09.  Separability Clause......................................................................15
         SECTION 1.10.  Benefits of Agreement....................................................................16
         SECTION 1.11.  Governing Law............................................................................16
         SECTION 1.12.  Legal Holidays...........................................................................16
         SECTION 1.13.  Counterparts.............................................................................16
         SECTION 1.14.  Inspection of Agreement..................................................................16
         SECTION 1.15.  Appointment of Financial Institution as Agent for the Company............................16

ARTICLE 2
         CERTIFICATE FORMS
         SECTION 2.01.  Forms of Certificates Generally..........................................................17
         SECTION 2.02.  Form of Purchase Contract Agent's Certificate of Authentication..........................18

ARTICLE 3
         THE SECURITIES
         SECTION 3.01.  Amount; Form and Denominations...........................................................18
         SECTION 3.02.  Rights and Obligations Evidenced by the Certificates.....................................18
         SECTION 3.03.  Execution, Authentication, Delivery and Dating...........................................19
         SECTION 3.04.  Temporary Certificates...................................................................20
         SECTION 3.05.  Registration; Registration of Transfer and Exchange......................................20
         SECTION 3.06.  Book-entry Interests.....................................................................22
         SECTION 3.07.  Notices to Holders.......................................................................22
         SECTION 3.08.  Appointment of Successor Depositary......................................................23
         SECTION 3.09.  Definitive Certificates..................................................................23
         SECTION 3.10.  Mutilated, Destroyed, Lost and Stolen Certificates.......................................23
         SECTION 3.11.  Persons Deemed Owners....................................................................24
         SECTION 3.12.  Cancellation.............................................................................25
         SECTION 3.13.  Creation of Treasury Peps Units by Substitution of Treasury Securities...................26
         SECTION 3.14.  Reestablishment of Peps Units............................................................27
</TABLE>

<PAGE>   3

<TABLE>
<CAPTION>
                                                                                                               PAGE
                                                                                                               ----
<S>                                                                                                            <C>
         SECTION 3.15.  Transfer of Collateral upon Occurrence of Termination Event..............................29
         SECTION 3.16.  No Consent to Assumption.................................................................29

ARTICLE 4
         THE PREFERRED SECURITIES, SENIOR DEFERRABLE NOTES AND APPLICABLE OWNERSHIP
         INTEREST OF THE TREASURY PORTFOLIO
         SECTION 4.01.  Interest Payments; Rights to Interest Payments Preserved.................................30
         SECTION 4.02.  Notice and Voting........................................................................31
         SECTION 4.03.  Distribution of Senior Deferrable Notes; Tax Event Redemption............................32

ARTICLE 5
         THE PURCHASE CONTRACTS
         SECTION 5.01.  Purchase of Shares of Common Stock.......................................................33
         SECTION 5.02.  Payment of Purchase Price................................................................35
         SECTION 5.03.  Issuance of Shares of Common Stock.......................................................40
         SECTION 5.04.  Adjustment of Settlement Rate............................................................41
         SECTION 5.05.  Notice of Adjustments and Certain Other Events...........................................47
         SECTION 5.06.  Termination Event; Notice................................................................48
         SECTION 5.07.  Early Settlement.........................................................................48
         SECTION 5.08.  Intentionally Omitted....................................................................50
         SECTION 5.09.  No Fractional Shares.....................................................................50
         SECTION 5.10.  Charges and Taxes........................................................................51

ARTICLE 6
         REMEDIES
         SECTION 6.01.  Unconditional Right of Holders to Purchase Shares of Common Stock........................51
         SECTION 6.02.  Restoration of Rights and Remedies.......................................................51
         SECTION 6.03.  Rights and Remedies Cumulative...........................................................51
         SECTION 6.04.  Delay or Omission Not Waiver.............................................................52
         SECTION 6.05.  Undertaking for Costs....................................................................52
         SECTION 6.06.  Waiver of Stay or Extension Laws.........................................................52

ARTICLE 7
         THE PURCHASE CONTRACT AGENT
         SECTION 7.01.  Certain Duties and Responsibilities......................................................53
         SECTION 7.02.  Notice of Default........................................................................54
         SECTION 7.03.  Certain Rights of Purchase Contract Agent................................................54
         SECTION 7.04.  Not Responsible for Recitals or Issuance of Securities...................................56
         SECTION 7.05.  May Hold Securities......................................................................56
         SECTION 7.06.  Money Held in Custody....................................................................56
         SECTION 7.07.  Compensation and Reimbursement...........................................................56
         SECTION 7.08.  Corporate Purchase Contract Agent Required; Eligibility..................................57
</TABLE>

                                       ii
<PAGE>   4

<TABLE>
<CAPTION>
                                                                                                               PAGE
                                                                                                               ----
<S>                                                                                                            <C>
         SECTION 7.09.  Resignation and Removal; Appointment of Successor........................................57
         SECTION 7.10.  Acceptance of Appointment by Successor...................................................58
         SECTION 7.11.  Merger, Conversion, Consolidation or Succession to Business..............................59
         SECTION 7.12.  Preservation of Information; Communications to Holders...................................59
         SECTION 7.13.  No Obligations of Purchase Contract Agent................................................60
         SECTION 7.14.  Tax Compliance...........................................................................60

ARTICLE 8
         SUPPLEMENTAL AGREEMENTS
         SECTION 8.01.  Supplemental Agreements Without Consent of Holders.......................................61
         SECTION 8.02.  Supplemental Agreements with Consent of Holders..........................................61
         SECTION 8.03.  Execution of Supplemental Agreements.....................................................62
         SECTION 8.04.  Effect of Supplemental Agreements........................................................63
         SECTION 8.05.  Reference to Supplemental Agreements.....................................................63

ARTICLE 9
         MERGER, CONSOLIDATION, SHARE EXCHANGE, SALE OR CONVEYANCE
         SECTION 9.01.  Covenant Not to Merge, Consolidate, Enter into a Share Exchange, Sell
                        or Convey Property Except under Certain Conditions.......................................63
         SECTION 9.02.  Rights and Duties of Successor Corporation...............................................64
         SECTION 9.03.  Officers' Certificate and Opinion of Counsel Given to Purchase Contract
                        Agent....................................................................................64

ARTICLE 10
         COVENANTS
         SECTION 10.01.  Performance under Purchase Contracts....................................................65
         SECTION 10.02.  Maintenance of Office or Agency.........................................................65
         SECTION 10.03.  Company to Reserve Common Stock.........................................................65
         SECTION 10.04.  Covenants as to Common Stock............................................................66
         SECTION 10.05.  Statements of Officers of the Company as to Default.....................................66
         SECTION 10.06.  ERISA...................................................................................66
</TABLE>

                                      iii
<PAGE>   5

         PURCHASE CONTRACT AGREEMENT, dated as of June 28, 2000, between VALERO
ENERGY CORPORATION, a Delaware corporation (the "COMPANY"), and THE BANK OF NEW
YORK, a New York banking corporation, acting as purchase contract agent for the
Holders of Securities (as defined herein) from time to time (the "PURCHASE
CONTRACT AGENT").

                                    RECITALS

         The Company has duly authorized the execution and delivery of this
Agreement and the Certificates evidencing the Securities.

         All things necessary to make the Purchase Contracts, when the
Certificates are executed by the Company and authenticated, executed on behalf
of the Holders and delivered by the Purchase Contract Agent, as provided in this
Agreement, the valid obligations of the Company, and to constitute these
presents a valid agreement of the Company, in accordance with its terms, have
been done. For and in consideration of the premises and the purchase of the
Securities by the Holders thereof, it is mutually agreed as follows:

                                    ARTICLE 1
            DEFINITIONS AND OTHER PROVISIONS OF GENERAL APPLICATIONS

         SECTION 1.01. Definitions.

         For all purposes of this Agreement, except as otherwise expressly
provided or unless the context otherwise requires:

         (a) the terms defined in this Article have the meanings assigned to
them in this Article and include the plural as well as the singular, and nouns
and pronouns of the masculine gender include the feminine and neuter genders;

         (b) all accounting terms not otherwise defined herein have the meanings
assigned to them in accordance with generally accepted accounting principles in
the United States;

         (c) the words "herein," "hereof" and "hereunder" and other words of
similar import refer to this Agreement as a whole and not to any particular
Article, Section, Exhibit or other subdivision;

         (d) the following terms have the meanings given to them in the
Declaration: (i) Applicable Ownership Interest; (ii) Applicable Principal
Amount; (iii) Guarantee; (iv) Primary Treasury Dealer; (v) Pro Rata, (vi)
Quotation Agent; (vii) Redemption Amount; (viii)

<PAGE>   6

Redemption Price; (ix) Remarketing, (x) Reset Rate, (xi) Tax Event Redemption,
(xii) Tax Event Redemption Date; (xiii) Two-Year Benchmark Treasury Rate; and
(xiv) Treasury Portfolio; and

         (e) the following terms have the meanings given to them in this Section
1.01(e):

         "ACT" has the meaning, with respect to any Holder, set forth in Section
1.04.

         "AFFILIATE" of any specified Person means any other Person directly or
indirectly controlling or controlled by or under direct or indirect common
control with such specified Person. For the purposes of this definition,
"control" when used with respect to any specified Person means the power to
direct the management and policies of such Person, directly or indirectly,
whether through the ownership of voting securities, by contract or otherwise;
and the terms "controlling" and "controlled" have meanings correlative to the
foregoing.

         "AGREEMENT" means this instrument as originally executed or as it may
from time to time be supplemented or amended by one or more agreements
supplemental hereto entered into pursuant to the applicable provisions hereof.

         "APPLICABLE MARKET VALUE" has the meaning set forth in Section 5.01.

         "APPLICANTS" has the meaning set forth in Section 7.12(b).

         "BANKRUPTCY CODE" means title 11 of the United States Code, or any
other law of the United States that from time to time provides a uniform system
of bankruptcy laws.

         "BENEFICIAL OWNER" means, with respect to a Book-Entry Interest, a
Person who is the beneficial owner of such Book-Entry Interest as reflected on
the books of the Depositary or on the books of a Person maintaining an account
with such Depositary (directly as a Depositary Participant or as an indirect
participant, in each case in accordance with the rules of such Depositary).

         "BOARD OF DIRECTORS" means the board of directors of the Company or a
duly authorized committee of that board.

         "BOARD RESOLUTION" means one or more resolutions of the Board of
Directors, a copy of which has been certified by the Secretary or an Assistant
Secretary of the Company, to have been duly adopted by the Board of Directors
and to be in full force and effect on the date of such certification and
delivered to the Purchase Contract Agent.

         "BOOK-ENTRY INTEREST" means a beneficial interest in a Global
Certificate, registered in the name of a Depositary or a nominee thereof,
ownership and transfers of which shall be maintained and made through book
entries by such Depositary as described in Section 3.06.

                                        2
<PAGE>   7

         "BUSINESS DAY" means any day other than a Saturday or Sunday or a day
on which banking institutions in New York City or San Antonio, Texas are
authorized or required by law or executive order to remain closed or a day on
which the Indenture Trustee or the Property Trustee is closed for business;
provided that for purposes of the second paragraph of Section 1.12 only, the
term "Business Day" shall also be deemed to exclude any day on which trading on
the New York Stock Exchange, Inc. is closed or suspended.

         "CASH SETTLEMENT" has the meaning set forth in Section 5.02(a)(i).

         "CERTIFICATE" means a PEPS Units Certificate or a Treasury PEPS Units
Certificate.

         "CLEARING AGENCY" means an organization registered as a "Clearing
Agency" pursuant to Section 17A of the Exchange Act that is acting as a
depositary for the Securities and in whose name, or in the name of a nominee of
that organization, shall be registered a Global Certificate and which shall
undertake to effect book-entry transfers and pledges of the Securities.

         "CLOSING PRICE" has the meaning set forth in Section 5.01.

         "CODE" means the Internal Revenue Code of 1986, as amended.

         "COLLATERAL" has the meaning set forth in Section 1.01 of the Pledge
Agreement.

         "COLLATERAL ACCOUNT" has the meaning set forth in Section 1.01 of the
Pledge Agreement.

         "COLLATERAL AGENT" means Bank One Trust Company, N.A., as Collateral
Agent under the Pledge Agreement until a successor Collateral Agent shall have
become such pursuant to the applicable provisions of the Pledge Agreement, and
thereafter "Collateral Agent" shall mean the Person who is then the Collateral
Agent thereunder.

         "COLLATERAL SUBSTITUTION" has the meaning set forth in Section 3.13.

         "COMMON STOCK" means the Valero Energy Corporation common stock, par
value $0.01 per share.

         "COMPANY" means the Person named as the "COMPANY" in the first
paragraph of this instrument until a successor shall have become such pursuant
to the applicable provision of this Agreement, and thereafter "Company" shall
mean such successor.

         "CONSTITUENT PERSON" has the meaning set forth in Section 5.04(b).

         "CORPORATE TRUST OFFICE" means the principal corporate trust office of
the Purchase Contract Agent at which, at any particular time, its corporate
trust business shall be administered, which office at the date hereof is located
at 101 Barclay Street, Floor 21 West, New York, New York 10286, Attention:
Corporate Trust Trustee Administration.

                                        3
<PAGE>   8

         "COUPON RATE" means the percentage rate per annum at which each Senior
Deferrable Note will bear interest initially and, on and after August 18, 2003,
the Reset Rate.

         "CURRENT MARKET PRICE" has the meaning set forth in Section 5.04(a)(8).

         "DECLARATION" means the Amended and Restated Declaration of Trust of
VEC Trust I, dated as of June 28, 2000, among the Company as sponsor, the
trustees named therein and the holders from time to time of individual
beneficial interests in the assets of the Trust.

         "DEPOSITARY" means a clearing agency registered under the Exchange Act
that is designated to act as Depositary for the Securities as contemplated by
Sections 3.06, 3.07, 3.08 and 3.09.

         "DEPOSITARY PARTICIPANT" means a broker, dealer, bank, other financial
institution or other Person for whom from time to time the Depositary effects
book entry transfers and pledges of securities deposited with the Depositary.

         "DTC" means The Depository Trust Company.

         "EARLY SETTLEMENT" has the meaning set forth in Section 5.07(a).

         "EARLY SETTLEMENT AMOUNT" has the meaning set forth in Section 5.07(a).

         "EARLY SETTLEMENT DATE" has the meaning set forth in Section 5.07(a).

         "EARLY SETTLEMENT RATE" has the meaning set forth in Section 5.07(b).

         "ERISA" means the Employee Retirement Income Security Act of 1974, as
amended.

         "EXCHANGE ACT" means the Securities Exchange Act of 1934, as amended,
and any statute successor thereto, in each case as amended from time to time,
and the rules and regulations promulgated thereunder.

         "EXPIRATION DATE" has the meaning set forth in Section 1.04(e).

         "EXPIRATION TIME" has the meaning set forth in Section 5.04(a)(6).

         "FAILED REMARKETING" has the meaning set forth in Section 5.02(b).

         "GLOBAL CERTIFICATE" means a Certificate that evidences all or part of
the Securities and is registered in the name of a Clearing Agency or a nominee
thereof.

                                        4
<PAGE>   9

         "HOLDER" means, with respect to a Security, the Person in whose name
the Security evidenced by a Certificate is registered in the Security Register;
provided, however, that in determining whether the Holders of the requisite
number of Securities have voted on any matter, then for the purpose of such
determination only (and not for any other purpose hereunder), if the Security
remains in the form of one or more Global Certificates and if the Depositary
which is the registered holder of such Global Certificate has sent an omnibus
proxy assigning voting rights to the Depositary Participants to whose accounts
the Securities are credited on the record date, the term "HOLDER" shall mean
such Depositary Participant acting at the direction of the Beneficial Owners.

         "INDENTURE" means the Senior Indenture, dated as of December 12, 1997,
between the Company and the Indenture Trustee (including any provisions of the
TIA that are deemed incorporated therein), as supplemented by the First
Supplemental Indenture dated as of June 28, 2000, pursuant to which the Senior
Deferrable Notes will be issued.

         "INDENTURE TRUSTEE" means The Bank of New York, a New York banking
corporation, as trustee under the Indenture, or any successor thereto.

         "ISSUER ORDER" or "ISSUER REQUEST" means a written order or request
signed in the name of the Company by its Chairman of the Board, its President or
one of its Vice Presidents, and by its Treasurer, an Assistant Treasurer, its
Secretary or an Assistant Secretary, and delivered to the Purchase Contract
Agent.

         "NON-ELECTING SHARE" has the meaning set forth in Section 5.04(b).

         "NYSE" has the meaning set forth in Section 5.01.

         "OFFICERS' CERTIFICATE" means a certificate signed by the Chairman of
the Board, its President or one of its Vice Presidents, and by the Treasurer, an
Assistant Treasurer, the Secretary or an Assistant Secretary of the Company, and
delivered to the Purchase Contract Agent. Any Officers' Certificate delivered
with respect to compliance with a condition or covenant provided for in this
Agreement 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 in rendering
         the Officers' Certificate;

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

                                        5
<PAGE>   10

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

         "OPINION OF COUNSEL" means a written opinion of counsel, who may be
counsel to the Company (and who may be an employee of the Company), and who
shall be reasonably acceptable to the Purchase Contract Agent. An opinion of
counsel may rely on certificates as to matters of fact.

         "OUTSTANDING SECURITIES" means, with respect to any Security and as of
the date of determination, all Securities evidenced by Certificates theretofore
authenticated, executed and delivered under this Agreement, except:

                  (i) If a Termination Event has occurred, (i) Treasury PEPS
         Units and (ii) PEPS Units for which the underlying Senior Deferrable
         Notes have been theretofore deposited with the Purchase Contract Agent
         in trust for the Holders of such PEPS Units;

                  (ii) Securities evidenced by Certificates theretofore
         cancelled by the Purchase Contract Agent or delivered to the Purchase
         Contract Agent for cancellation or deemed cancelled pursuant to the
         provisions of this Agreement; and

                  (iii) Securities evidenced by Certificates in exchange for or
         in lieu of which other Certificates have been authenticated, executed
         on behalf of the Holder and delivered pursuant to this Agreement, other
         than any such Certificate in respect of which there shall have been
         presented to the Purchase Contract Agent proof satisfactory to it that
         such Certificate is held by a bona fide purchaser in whose hands the
         Securities evidenced by such Certificate are valid obligations of the
         Company;

provided, however, that in determining whether the Holders of the requisite
number of the Securities have given any request, demand, authorization,
direction, notice, consent or waiver hereunder, Securities owned by the Company
or any Affiliate of the Company shall be disregarded and deemed not to be
Outstanding Securities, except that, in determining whether the Purchase
Contract Agent shall be protected in relying upon any such request, demand,
authorization, direction, notice, consent or waiver, only Securities that a
Responsible Officer of the Purchase Contract Agent knows to be so owned shall be
so disregarded. Securities so owned that have been pledged in good faith may be
regarded as Outstanding Securities if the pledgee establishes to the
satisfaction of the Purchase Contract Agent the pledgee's right so to act with
respect to such Securities and that the pledgee is not the Company or any
Affiliate of the Company.

         "PAYMENT DATE" means each February 18, May 18, August 18 and November
18, commencing August 18, 2000.

                                        6
<PAGE>   11

         "PEPS UNIT" means the collective rights and obligations of a Holder of
a PEPS Units Certificate in respect of a Preferred Security, the Senior
Deferrable Notes or an appropriate Applicable Ownership Interest of the Treasury
Portfolio, as the case may be, subject in each case to the Pledge thereof, and
the related Purchase Contract; provided, that the appropriate Applicable
Ownership Interest (as specified in clause (B) of the definition of such term)
of the Treasury Portfolio shall not be subject to the Pledge.

         "PEPS UNITS CERTIFICATE" means a certificate evidencing the rights and
obligations of a Holder in respect of the number of PEPS Units specified on such
certificate.

         "PERMITTED INVESTMENTS" has the meaning set forth in Section 1.01 of
the Pledge Agreement.

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

         "PLAN" means an employee benefit plan that is subject to ERISA, a plan
or individual retirement account that is subject to Section 4975 of the Code or
any entity whose assets are considered assets of any such plan.

         "PLEDGE" means the pledge under the Pledge Agreement of the Preferred
Securities, the Senior Deferrable Notes, the Treasury Securities or the
appropriate Applicable Ownership Interest (as specified in clause (A) of the
definition of such term) of the Treasury Portfolio, in each case constituting a
part of the Securities.

         "PLEDGE AGREEMENT" means the Pledge Agreement, dated as of June 28,
2000, among the Company, the Collateral Agent, the Securities Intermediary and
the Purchase Contract Agent, on its own behalf and as attorney-in-fact for the
Holders from time to time of the Securities.

         "PLEDGED SENIOR DEFERRABLE NOTES" has the meaning set forth in the
Pledge Agreement.

         "PLEDGED PREFERRED SECURITIES" has the meaning set forth in the Pledge
Agreement.

         "PREDECESSOR CERTIFICATE" means a Predecessor PEPS Units Certificate or
a Predecessor Treasury PEPS Units Certificate.

         "PREDECESSOR PEPS UNITS CERTIFICATE" of any particular PEPS Units
Certificate means every previous PEPS Units Certificate evidencing all or a
portion of the rights and obligations of the Company and the Holder under the
PEPS Units evidenced thereby; and, for the purposes of this definition, any PEPS
Units Certificate authenticated and delivered under Section 3.10 in exchange for
or in lieu of a mutilated, destroyed, lost or stolen PEPS Units Certificate
shall be

                                        7
<PAGE>   12

deemed to evidence the same rights and obligations of the Company and the Holder
as the mutilated, destroyed, lost or stolen PEPS Units Certificate.

         "PREDECESSOR TREASURY PEPS UNITS CERTIFICATE" of any particular
Treasury PEPS Units Certificate means every previous Treasury PEPS Units
Certificate evidencing all or a portion of the rights and obligations of the
Company and the Holder under the Treasury PEPS Units evidenced thereby; and, for
the purposes of this definition, any Treasury PEPS Units Certificate
authenticated and delivered under Section 3.10 in exchange for or in lieu of a
mutilated, destroyed, lost or stolen Treasury PEPS Units Certificate shall be
deemed to evidence the same rights and obligations of the Company and the Holder
as the mutilated, destroyed, lost or stolen Treasury PEPS Units Certificate.

         "PREFERRED SECURITIES" means the Preferred Securities of the Trust,
each having a stated liquidation amount of $25, representing preferred undivided
beneficial interests in the assets of the Trust.

         "PROCEEDS" has the meaning set forth in Section 1.01 of the Pledge
Agreement.

         "PROPERTY TRUSTEE" means The Bank of New York, as initial property
trustee under the Declaration, or any successors thereto that is a financial
institution unaffiliated with the Company.

         "PURCHASE CONTRACT" means, with respect to any Security, the contract
forming a part of such Security and obligating the Company to sell, and the
Holder of such Security to purchase, shares of Common Stock on the terms and
subject to the conditions set forth in Article Five hereof.

         "PURCHASE CONTRACT AGENT" means the Person named as the "PURCHASE
CONTRACT AGENT" in the first paragraph of this Agreement until a successor
Purchase Contract Agent shall have become such pursuant to the applicable
provisions of this Agreement, and thereafter "PURCHASE CONTRACT AGENT" shall
mean such Person.

         "PURCHASE CONTRACT SETTLEMENT DATE" means August 18, 2003.

         "PURCHASE CONTRACT SETTLEMENT FUND" has the meaning set forth in
Section 5.03.

         "PURCHASE PRICE" has the meaning set forth in Section 5.01.

         "PURCHASED SHARES" has the meaning set forth in Section 5.04(a)(6).

         "RECORD DATE" for the interest payable on any Payment Date means, as to
any Global Certificate, the Business Day next preceding such Payment Date, and
as to any other Certificate, the fifteenth Business Day prior to such Payment
Date.

                                        8
<PAGE>   13

         "REFERENCE DEALER" means a dealer engaged in trading of convertible
securities.

         "REFERENCE PRICE" has the meaning set forth in Section 5.01.

         "REMARKETING AGENT" has the meaning set forth in Section 5.02(b).

         "REMARKETING AGREEMENT" means the Remarketing Agreement, dated as of
June 28, 2000, between the Company and the Remarketing Agent.

         "REORGANIZATION EVENT" has the meaning set forth in Section 5.04(b).

         "RESPONSIBLE OFFICER" means, with respect to the Purchase Contract
Agent, any officer of the Purchase Contract Agent assigned by the Purchase
Contract Agent to administer this Purchase Contract Agreement.

         "SECURITIES INTERMEDIARY" means Bank One Trust Company, N.A., as
Securities Intermediary under the Pledge Agreement until a successor Securities
Intermediary shall have become such pursuant to the applicable provisions of the
Pledge Agreement, and thereafter "Securities Intermediary" shall mean such
successor.

         "SECURITY" means a PEPS Unit or a Treasury PEPS Unit, as the case may
be.

         "SECURITY REGISTER" and "SECURITIES REGISTRAR" have the respective
meanings set forth in Section 3.05.

         "SENIOR DEFERRABLE NOTES" means the series of Senior Deferrable Notes
issued by the Company under the Indenture and held by the Property Trustee.

         "SETTLEMENT RATE" has the meaning set forth in Section 5.01.

         "STATED AMOUNT" means $25.

         "TERMINATION DATE" means the date, if any, on which a Termination Event
occurs.

         "TERMINATION EVENT" means the occurrence of any of the following
events:

                  (i) at any time on or prior to the Purchase Contract
         Settlement Date, a judgment, decree or court order shall have been
         entered granting relief under the Bankruptcy Code, adjudicating the
         Company to be insolvent, or approving as properly filed a petition
         seeking reorganization or liquidation of the Company or any other
         similar applicable Federal or State law, and, unless such judgment,
         decree or order shall have been entered within 60 days prior to the
         Purchase Contract Settlement Date, such decree or order shall have
         continued undischarged and unstayed for a period of 60 days;

                                        9
<PAGE>   14

                  (ii) a judgment, decree or court order for the appointment of
         a receiver or liquidator or trustee or assignee in bankruptcy or
         insolvency of the Company or of its property, or for the termination or
         liquidation of its affairs, shall have been entered, and, unless such
         judgment, decree or order shall have been entered within 60 days prior
         to the Purchase Contract Settlement Date, such judgment, decree or
         order shall have continued undischarged and unstayed for a period of 60
         days; or

                  (iii) at any time on or prior to the Purchase Contract
         Settlement Date, the Company shall file a petition for relief under the
         Bankruptcy Code, or shall consent to the filing of a bankruptcy
         proceeding against it, or shall file a petition or answer or consent
         seeking reorganization or liquidation under the Bankruptcy Code or any
         other similar applicable Federal or State law, or shall consent to the
         filing of any such petition, or shall consent to the appointment of a
         receiver or liquidator or trustee or assignee in bankruptcy or
         insolvency of it or of its property, or shall make an assignment for
         the benefit of creditors, or shall admit in writing its inability to
         pay its debts generally as they become due.

         "THRESHOLD APPRECIATION PRICE" has the meaning set forth in Section
5.01.

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

         "TRADING DAY" has the meaning set forth in Section 5.01.

         "TREASURY PEPS UNIT" means, following the substitution of Treasury
Securities for Preferred Securities or Senior Deferrable Notes as collateral to
secure a Holder's obligations under the Purchase Contract, the collective rights
and obligations of a Holder of a Treasury PEPS Units Certificate in respect of
such Treasury Securities, subject to the Pledge thereof, and the related
Purchase Contract.

         "TREASURY PEPS UNITS CERTIFICATE" means a certificate evidencing the
rights and obligations of a Holder in respect of the number of Treasury PEPS
Units specified on such certificate.

         "TREASURY SECURITIES" means zero-coupon U.S. Treasury Securities (CUSIP
No. 912820BG1) which mature on August 15, 2003.

         "TRUST" means VEC Trust I, a statutory business formed under the laws
of the State of Delaware, or any successor thereto by merger or consolidation.

         "UNDERWRITING AGREEMENT" means the Underwriting Agreement, dated as of
June 22, 2000, between the Company, VEC Trust I and the Underwriters identified
in Schedule 1 thereto.

                                       10
<PAGE>   15

         "VICE PRESIDENT" means any vice president, whether or not designated by
a number or a word or words added before or after the title "vice president."

         SECTION 1.02.  Compliance Certificates and Opinions.

         Except as otherwise expressly provided by this Agreement, upon any
application or request by the Company to the Purchase Contract Agent to take any
action in accordance with any provision of this Agreement, the Company shall
furnish to the Purchase Contract Agent an Officers' Certificate stating that all
conditions precedent, if any, provided for in this Agreement relating to the
proposed action have been complied with and, if requested by the Purchase
Contract Agent, an Opinion of Counsel stating that, in the opinion of such
counsel, all such conditions precedent, if any, have been complied with, except
that in the case of any such application or request as to which the furnishing
of such documents is specifically required by any provision of this Agreement
relating to such particular application or request, no additional certificate or
opinion need be furnished.

         Every certificate or opinion with respect to compliance with a
condition or covenant provided for in this Agreement shall include:

                  (i) a statement that each individual signing such certificate
         or opinion has read such covenant or condition and the definitions
         herein relating thereto;

                  (ii) a brief statement as to the nature and scope of the
         examination or investigation upon which the statements or opinions
         contained in such certificate or opinion are based;

                  (iii) a statement that, in the opinion of each such
         individual, he or she has made such examination or investigation as is
         necessary to enable such individual 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
         individual, such condition or covenant has been complied with.

         SECTION 1.03.  Form of Documents Delivered to Purchase Contract Agent.

         In any case where several matters are required to be certified by, or
covered by an opinion of, any specified Person, it is not necessary that all
such matters be certified by, or covered by the opinion of, only one such
Person, or that they be so certified or covered by only one document, but one
such Person may certify or give an opinion with respect to some matters and one
or more other such Persons as to other matters, and any such Person may certify
or give an opinion as to

                                       11
<PAGE>   16

such matters in one or several documents. Any certificate or opinion of an
officer of the Company may be based, insofar as it relates to legal matters,
upon a certificate or opinion of, or representations by, counsel, unless such
officer knows, or in the exercise of reasonable care should know, that the
certificate or opinion or representations with respect to the matters upon which
his certificate or opinion is based are erroneous. Any such certificate or
Opinion of Counsel may be based, insofar as it relates to factual matters, upon
a certificate or opinion of, or representations by, an officer or officers of
the Company stating that the information with respect to such factual matters is
in the possession of the Company unless such counsel knows, or in the exercise
of reasonable care should know, that the certificate or opinion or
representations with respect to such matters are erroneous.

         Where any Person is required to make, give or execute two or more
applications, requests, consents, certificates, statements, opinions or other
instruments under this Agreement, they may, but need not, be consolidated and
form one instrument.

         SECTION 1.04. Acts of Holders; Record Dates.

         (a) Any request, demand, authorization, direction, notice, consent,
waiver or other action provided by this Agreement to be given or taken by
Holders may be embodied in and evidenced by one or more instruments of
substantially similar tenor signed by such Holders in person or by an agent duly
appointed in writing; and, except as herein otherwise expressly provided, such
action shall become effective when such instrument or instruments are delivered
to the Purchase Contract Agent and, where it is hereby expressly required, to
the Company. Such instrument or instruments (and the action embodied therein and
evidenced thereby) are herein sometimes referred to as the "ACT" of the Holders
signing such instrument or instruments. Proof of execution of any such
instrument or of a writing appointing any such agent shall be sufficient for any
purpose of this Agreement and (subject to Section 7.01) conclusive in favor of
the Purchase Contract Agent and the Company, if made in the manner provided in
this Section.

         (b) The fact and date of the execution by any Person of any such
instrument or writing may be proved in any manner which the Purchase Contract
Agent deems sufficient.

         (c) The ownership of Securities shall be proved by the PEPS Units
Register or the Treasury PEPS Units Register, as the case may be.

         (d) Any request, demand, authorization, direction, notice, consent,
waiver or other Act of the Holder of any Security shall bind every future Holder
of the same Security and the Holder of every Certificate evidencing such
Security issued upon the registration of transfer thereof or in exchange
therefor or in lieu thereof in respect of anything done, omitted or suffered to
be done by the Purchase Contract Agent or the Company in reliance thereon,
whether or not notation of such action is made upon such Certificate.

         (e) The Company may set any date as a record date for the purpose of
determining the

                                       12
<PAGE>   17

Holders of Outstanding Securities entitled to give, make or take any request,
demand, authorization, direction, notice, consent, waiver or other action
provided or permitted by this Agreement to be given, made or taken by Holders of
Securities. If any record date is set pursuant to this paragraph, the Holders of
the Outstanding PEPS Units and the Outstanding Treasury PEPS Units, as the case
may be, on such record date, and no other Holders, shall be entitled to take the
relevant action with respect to the PEPS Units or the Treasury PEPS Units, as
the case may be, whether or not such Holders remain Holders after such record
date; provided that no such action shall be effective hereunder unless taken
prior to or on the applicable Expiration Date by Holders of the requisite number
of Outstanding Securities on such record date. Nothing contained in this
paragraph shall be construed to prevent the Company from setting a new record
date for any action for which a record date has previously been set pursuant to
this paragraph (whereupon the record date previously set shall automatically and
with no action by any Person be cancelled and be of no effect), and nothing
contained in this paragraph shall be construed to render ineffective any action
taken by Holders of the requisite number of Outstanding Securities on the date
such action is taken. Promptly after any record date is set pursuant to this
paragraph, the Company, at its own expense, shall cause notice of such record
date, the proposed action by Holders and the applicable Expiration Date to be
given to the Purchase Contract Agent in writing and to each Holder of Securities
in the manner set forth in Section 1.06.

         With respect to any record date set pursuant to this Section, the
Company may designate any date as the "EXPIRATION DATE" and from time to time
may change the Expiration Date to any earlier or later day; provided that no
such change shall be effective unless notice of the proposed new Expiration Date
is given to the Purchase Contract Agent in writing, and to each Holder of
Securities in the manner set forth in Section 1.06, prior to or on the existing
Expiration Date. If an Expiration Date is not designated with respect to any
record date set pursuant to this Section, the Company shall be deemed to have
initially designated the 180th day after such record date as the Expiration Date
with respect thereto, subject to its right to change the Expiration Date as
provided in this paragraph. Notwithstanding the foregoing, no Expiration Date
shall be later than the 180th day after the applicable record date.

         SECTION 1.05. Notices.

         Any notice or communication is duly given if in writing and delivered
in Person or mailed by first-class mail (registered or certified, return receipt
requested), telecopier (with receipt confirmed) or overnight air courier
guaranteeing next day delivery, to the others' address; provided that notice
shall be deemed given to the Purchase Contract Agent only upon receipt thereof:

                                       13
<PAGE>   18

         If to the Purchase Contract Agent:

                  The Bank of New York
                  101 Barclay Street
                  Floor 21 West
                  New York, New York 10286
                  Telecopier No.: (212) 815-5915
                  Attention: Corporate Trust Trustee Administration

         If to the Company:
                  Valero Energy Corporation
                  One Valero Energy Place
                  P.O. Box 500
                  San Antonio, Texas 78212 (78292-0500)
                  Telecopier No.: (210) 370-2988
                  Attention: Jay D. Browning

         With a copy to:
                  Valero Energy Corporation
                  One Valero Energy Place
                  P.O. Box 500
                  San Antonio, Texas  78212 (78292-0500)
                  Telecopier No.: (210) 370-2497
                  Attention: Donna M. Titzman

         If to the Collateral Agent:
                  Bank One Trust Company, N.A.
                  One North State Street, 9th Floor
                  Chicago, Illinois 60670-0126
                  Telecopier No.: (312) 407-1708
                  Attention: Corporate Trust Administration

         If to the Property Trustee:
                  The Bank of New York
                  101 Barclay Street
                  Floor 21 West
                  New York, New York 10286
                  Telecopier No.: (212) 815-5915
                  Attention: Corporate Trust Trustee Administration

                                       14
<PAGE>   19

         If to the Indenture Trustee:
                  The Bank of New York
                  101 Barclay Street
                  Floor 21 West
                  New York, New York 10286
                  Telecopier No.: (212) 815-5915
                  Attention: Corporate Trust Trustee Administration

         SECTION 1.06. Notice to Holders; Waiver.

         Where this Agreement provides for notice to Holders of any event, such
notice shall be sufficiently given (unless otherwise herein expressly provided)
if in writing and mailed, first-class postage prepaid, to each Holder affected
by such event, at its address as it appears in the applicable Register, not
later than the latest date, and not earlier than the earliest date, prescribed
for the giving of such notice. In any case where notice to Holders is given by
mail, neither the failure to mail such notice, nor any defect in any notice so
mailed to any particular Holder shall affect the sufficiency of such notice with
respect to other Holders. Where this Agreement provides for notice in any
manner, such notice may be waived in writing by the Person entitled to receive
such notice, either before or after the event, and such waiver shall be the
equivalent of such notice. Waivers of notice by Holders shall be filed with the
Purchase Contract Agent, but such filing shall not be a condition precedent to
the validity of any action taken in reliance upon such waiver.

         In case by reason of the suspension of regular mail service or by
reason of any other cause it shall be impracticable to give such notice by mail,
then such notification as shall be made with the approval of the Purchase
Contract Agent shall constitute a sufficient notification for every purpose
hereunder.

         SECTION 1.07. Effect of Headings and Table of Contents.

         The Article and Section headings herein and the Table of Contents are
for convenience only and shall not affect the construction hereof.

         SECTION 1.08. Successors and Assigns.

         All covenants and agreements in this Agreement by the Company and the
Purchase Contract Agent shall bind their respective successors and assigns,
whether so expressed or not.

         SECTION 1.09. Separability Clause.

         In case any provision in this Agreement or in the Securities shall be
invalid, illegal or unenforceable, the validity, legality and enforceability of
the remaining provisions hereof and thereof shall not in any way be affected or
impaired thereby.

                                       15
<PAGE>   20

         SECTION 1.10. Benefits of Agreement.

         Nothing contained in this Agreement or in the Securities, express or
implied, shall give to any Person, other than the parties hereto and their
successors hereunder and, to the extent provided hereby, the Holders, any
benefits or any legal or equitable right, remedy or claim under this Agreement.
The Holders from time to time shall be beneficiaries of this Agreement and shall
be bound by all of the terms and conditions hereof and of the Securities
evidenced by their Certificates by their acceptance of delivery of such
Certificates.

         SECTION 1.11. Governing Law.

         This Agreement and the Securities shall be governed by, and construed
in accordance with, the laws of the State of New York.

         SECTION 1.12. Legal Holidays.

         In any case where any Payment Date, any Purchase Contract Settlement
Date or Early Settlement Date shall not be a Business Day, (notwithstanding any
other provision of this Agreement or the Securities), Purchase Contracts shall
not be performed and Early Settlement shall not be effected on such date, but
Purchase Contracts shall be performed or Early Settlement effected, as
applicable, on the next succeeding Business Day with the same force and effect
as if made on such Payment Date, Purchase Contract Settlement Date, or Early
Settlement Date, as applicable, provided that no interest shall accrue or be
payable by the Company or to any Holder for the period from and after any such
Purchase Contract Settlement Date, or Early Settlement Date, as applicable,
except that, if such next succeeding Business Day is in the next succeeding
calendar year, such payment shall be made on the immediately preceding Business
Day with the same force and effect as if made on such Purchase Contract
Settlement Date, or Early Settlement Date, as applicable.

         SECTION 1.13. Counterparts.

         This Agreement may be executed in any number of counterparts by the
parties hereto on separate counterparts, each of which, when so executed and
delivered, shall be deemed an original, but all such counterparts shall together
constitute one and the same instrument.

         SECTION 1.14. Inspection of Agreement.

         A copy of this Agreement shall be available at all reasonable times
during normal business hours at the Corporate Trust Office for inspection by any
Holder or Beneficial Owner.

         SECTION 1.15. Appointment of Financial Institution as Agent for the
Company.

         The Company may appoint a financial institution (which may be the
Collateral Agent) to

                                       16
<PAGE>   21

act as its agent in performing its obligations and in accepting and enforcing
performance of the obligations of the Purchase Contract Agent and the Holders,
under this Agreement and the Purchase Contracts, by giving notice of such
appointment in the manner provided in Section 1.05 hereof. Any such appointment
shall not relieve the Company in any way from its obligations hereunder.

                                    ARTICLE 2
                                CERTIFICATE FORMS

         SECTION 2.01. Forms of Certificates Generally.

         The Certificates (including the form of Purchase Contract forming part
of each Security evidenced thereby) shall be in substantially the form set forth
in Exhibit A hereto (in the case of Certificates evidencing PEPS Units) or
Exhibit B hereto (in the case of Certificates evidencing Treasury PEPS Units),
with such letters, numbers or other marks of identification or designation and
such legends or endorsements printed, lithographed or engraved thereon as may be
required by the rules of any securities exchange on which the Securities are
listed or any depositary therefor, or as may, consistently herewith, be
determined by the officers of the Company executing such Certificates, as
evidenced by their execution of the Certificates.

         The definitive Certificates shall be printed, lithographed or engraved
on steel engraved borders or may be produced in any other manner, all as
determined by the officers of the Company executing the Securities evidenced by
such Certificates, consistent with the provisions of this Agreement, as
evidenced by their execution thereof.

         Every Global Certificate authenticated, executed on behalf of the
Holders and delivered hereunder shall bear a legend in substantially the
following form:

         "THIS CERTIFICATE IS A GLOBAL CERTIFICATE WITHIN THE MEANING OF THE
         PURCHASE CONTRACT AGREEMENT HEREINAFTER REFERRED TO AND IS REGISTERED
         IN THE NAME OF THE DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION
         (THE "DEPOSITARY"), OR A NOMINEE OF THE DEPOSITARY. THIS CERTIFICATE IS
         EXCHANGEABLE FOR CERTIFICATES REGISTERED IN THE NAME OF A PERSON OTHER
         THAN THE DEPOSITARY OR ITS NOMINEE ONLY IN THE LIMITED CIRCUMSTANCES
         DESCRIBED IN THE PURCHASE CONTRACT AGREEMENT AND NO TRANSFER OF THIS
         CERTIFICATE (OTHER THAN A TRANSFER OF THIS CERTIFICATE AS A WHOLE BY
         THE DEPOSITARY TO A NOMINEE OF THE DEPOSITARY OR BY A NOMINEE OF THE
         DEPOSITARY TO THE DEPOSITARY OR ANOTHER NOMINEE OF THE DEPOSITARY) MAY
         BE REGISTERED EXCEPT IN LIMITED CIRCUMSTANCES.

                                       17
<PAGE>   22

         UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF
         THE DEPOSITARY FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND
         ANY CERTIFICATE ISSUED IS REQUESTED IN THE NAME OF CEDE & CO. OR SUCH
         OTHER NAME AS REGISTERED BY AN AUTHORIZED REPRESENTATIVE OF THE
         DEPOSITARY (AND ANY PAYMENT HEREON IS MADE TO CEDE & CO. OR TO SUCH
         OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF THE
         DEPOSITARY), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR
         OTHERWISE BY OR TO ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER
         HEREOF, CEDE & CO., HAS AN INTEREST HEREIN."

         SECTION 2.02. Form of Purchase Contract Agent's Certificate of
Authentication.

         The form of the Purchase Contract Agent's certificate of authentication
of the Securities shall be in substantially the form set forth on the form of
the applicable Certificates.

                                    ARTICLE 3
                                 THE SECURITIES

         SECTION 3.01. Amount; Form and Denominations.

         The aggregate number of Securities evidenced by Certificates
authenticated, executed on behalf of the Holders and delivered hereunder is
limited to 6,000,000 (subject to increase up to a maximum of 900,000 to the
extent the over-allotment option granted to the Underwriters in the Underwriting
Agreement is exercised), except for Certificates authenticated, executed and
delivered upon registration of transfer of, in exchange for, or in lieu of,
other Certificates pursuant to Section 3.04, 3.05, 3.10, 3.13, 3.14, 5.07 or
8.05.

         The Certificates shall be issuable only in registered form and only in
denominations of a single PEPS Unit or Treasury PEPS Unit and any integral
multiple thereof.

         SECTION 3.02. Rights and Obligations Evidenced by the Certificates.

         Each PEPS Units Certificate shall evidence the number of PEPS Units
specified therein, with each such PEPS Unit representing (1) the ownership by
the Holder thereof of a beneficial interest in a Preferred Security, a Senior
Deferrable Note or the Applicable Ownership Interest of the Treasury Portfolio,
as the case may be, subject to the Pledge of such Preferred Security, such
Senior Note or the Applicable Ownership Interest (as specified in clause (A) of
the definition of such term) of the Treasury Portfolio, as the case may be, by
such Holder pursuant to the Pledge Agreement, and (2) the rights and obligations
of the Holder thereof and the Company under one Purchase Contract. The Purchase
Contract Agent as attorney-in-fact for, and on behalf of, the

                                       18
<PAGE>   23

Holder of each PEPS Unit shall pledge, pursuant to the Pledge Agreement, the
Preferred Security, the Senior Note or the Applicable Ownership Interest (as
specified in clause (A) of the definition of such term) of the Treasury
Portfolio, as the case may be, forming a part of such PEPS Unit, to the
Collateral Agent and grant to the Collateral Agent a security interest in the
right, title and interest of such Holder in such Preferred Security, such Senior
Note or the Applicable Ownership Interest (as specified in clause (A) of the
definition of such term) of the Treasury Portfolio, as the case may be, for the
benefit of the Company, to secure the obligation of the Holder under each
Purchase Contract to purchase shares of Common Stock.

         Upon the formation of a Treasury PEPS Unit pursuant to Section 3.13,
each Treasury PEPS Units Certificate shall evidence the number of Treasury PEPS
Units specified therein, with each such Treasury PEPS Unit representing (1) the
ownership by the Holder thereof of a 1/40 undivided beneficial interest in a
Treasury Security with a principal amount equal to $1,000, subject to the Pledge
of such Treasury Security by such Holder pursuant to the Pledge Agreement, and
(2) the rights and obligations of the Holder thereof and the Company under one
Purchase Contract.

         Prior to the purchase of shares of Common Stock under each Purchase
Contract, such Purchase Contracts shall not entitle the Holder of a Security to
any of the rights of a holder of shares of Common Stock, including, without
limitation, the right to vote or receive any dividends or other payments or to
consent or to receive notice as a shareholder in respect of the meetings of
shareholders or for the election of directors of the Company or for any other
matter, or any other rights whatsoever as a shareholder of the Company.

         SECTION 3.03. Execution, Authentication, Delivery and Dating.

         Subject to the provisions of Sections 3.13 and 3.14 hereof, upon the
execution and delivery of this Agreement, and at any time and from time to time
thereafter, the Company may deliver Certificates executed by the Company to the
Purchase Contract Agent for authentication, execution on behalf of the Holders
and delivery, together with its Issuer Order for authentication of such
Certificates, and the Purchase Contract Agent in accordance with such Issuer
Order shall authenticate, execute on behalf of the Holders and deliver such
Certificates.

         The Certificates shall be executed on behalf of the Company by its
Chairman of the Board, its President or one of its Vice Presidents. The
signature of any of these officers on the Certificates may be manual or
facsimile.

         Certificates bearing the manual or facsimile signatures of individuals
who were at any time the proper officers of the Company shall bind the Company,
notwithstanding that such individuals or any of them have ceased to hold such
offices prior to the authentication and delivery of such Certificates or did not
hold such offices at the date of such Certificates.

         No Purchase Contract evidenced by a Certificate shall be valid until
such Certificate has

                                       19
<PAGE>   24

been executed on behalf of the Holder by the manual signature of an authorized
signatory of the Purchase Contract Agent, as such Holder's attorney-in-fact.
Such signature by an authorized signatory of the Purchase Contract Agent shall
be conclusive evidence that the Holder of such Certificate has entered into the
Purchase Contracts evidenced by such Certificate.

         Each Certificate shall be dated the date of its authentication.

         No Certificate shall be entitled to any benefit under this Agreement or
be valid or obligatory for any purpose unless there appears on such Certificate
a certificate of authentication substantially in the form provided for herein
executed by an authorized signatory of the Purchase Contract Agent by manual
signature, and such certificate upon any Certificate shall be conclusive
evidence, and the only evidence, that such Certificate has been duly
authenticated and delivered hereunder.

         SECTION 3.04. Temporary Certificates.

         Pending the preparation of definitive Certificates, the Company shall
execute and deliver to the Purchase Contract Agent, and the Purchase Contract
Agent shall authenticate, execute on behalf of the Holders, and deliver, in lieu
of such definitive Certificates, temporary Certificates which are in
substantially the form set forth in Exhibit A or Exhibit B hereto, as the case
may be, with such letters, numbers or other marks of identification or
designation and such legends or endorsements printed, lithographed or engraved
thereon as may be required by the rules of any securities exchange on which the
PEPS Units or Treasury PEPS Units, as the case may be, are listed, or as may,
consistently herewith, be determined by the officers of the Company executing
such Certificates, as evidenced by their execution of the Certificates.

         If temporary Certificates are issued, the Company will cause definitive
Certificates to be prepared without unreasonable delay. After the preparation of
definitive Certificates, the temporary Certificates shall be exchangeable for
definitive Certificates upon surrender of the temporary Certificates at the
Corporate Trust Office, at the expense of the Company and without charge to the
Holder. Upon surrender for cancellation of any one or more temporary
Certificates, the Company shall execute and deliver to the Purchase Contract
Agent, and the Purchase Contract Agent shall authenticate, execute on behalf of
the Holder, and deliver in exchange therefor, one or more definitive
Certificates of like tenor and denominations and evidencing a like number of
Securities as the temporary Certificate or Certificates so surrendered. Until so
exchanged, the temporary Certificates shall in all respects evidence the same
benefits and the same obligations with respect to the Securities, evidenced
thereby as definitive Certificates.

         SECTION 3.05. Registration; Registration of Transfer and Exchange.

         The Purchase Contract Agent shall keep at the Corporate Trust Office a
register (the "SECURITY REGISTER") in which, subject to such reasonable
regulations as it may prescribe, the Purchase Contract Agent shall provide for
the registration of Certificates and of transfers of

                                       20
<PAGE>   25

Certificates (the Purchase Contract Agent, in such capacity, the "SECURITY
REGISTRAR"). The Security Registrar shall record separately the registration and
transfer of the Certificates evidencing PEPS Units and Treasury PEPS Units

         Upon surrender for registration of transfer of any Certificate at the
Corporate Trust Office, the Company shall execute and deliver to the Purchase
Contract Agent, and the Purchase Contract Agent shall authenticate, execute on
behalf of the designated transferee or transferees, and deliver, in the name of
the designated transferee or transferees, one or more new Certificates of any
authorized denominations, like tenor, and evidencing a like number of PEPS Units
or Treasury PEPS Units, as the case may be.

         At the option of the Holder, Certificates may be exchanged for other
Certificates, of any authorized denominations and evidencing a like number of
PEPS Units or Treasury PEPS Units, as the case may be, upon surrender of the
Certificates to be exchanged at the Corporate Trust Office. Whenever any
Certificates are so surrendered for exchange, the Company shall execute and
deliver to the Purchase Contract Agent, and the Purchase Contract Agent shall
authenticate, execute on behalf of the Holder, and deliver the Certificates
which the Holder making the exchange is entitled to receive.

         All Certificates issued upon any registration of transfer or exchange
of a Certificate shall evidence the ownership of the same number of PEPS Units
or Treasury PEPS Units, as the case may be, and be entitled to the same benefits
and subject to the same obligations, under this Agreement as the PEPS Units or
Treasury PEPS Units, as the case may be, evidenced by the Certificate
surrendered upon such registration of transfer or exchange.

         Every Certificate presented or surrendered for registration of transfer
or exchange shall (if so required by the Purchase Contract Agent) be duly
endorsed, or be accompanied by a written instrument of transfer in form
satisfactory to the Company and the Purchase Contract Agent duly executed, by
the Holder thereof or its attorney duly authorized in writing.

         No service charge shall be made for any registration of transfer or
exchange of a Certificate, but the Company and the Purchase Contract Agent may
require payment from the Holder of a sum sufficient to cover any tax or other
governmental charge that may be imposed in connection with any registration of
transfer or exchange of Certificates, other than any exchanges pursuant to
Sections 3.06 and 8.05 not involving any transfer.

         Notwithstanding the foregoing, the Company shall not be obligated to
execute and deliver to the Purchase Contract Agent, and the Purchase Contract
Agent shall not be obligated to authenticate, execute on behalf of the Holder
and deliver any Certificate in exchange for any other Certificate presented or
surrendered for registration of transfer or for exchange on or after the
Business Day immediately preceding the earlier of the Purchase Contract
Settlement Date or the Termination Date. In lieu of delivery of a new
Certificate, upon satisfaction of the applicable conditions specified above in
this Section and receipt of appropriate registration or transfer instructions
from such Holder, the Purchase Contract Agent shall:

                                       21
<PAGE>   26

                  (i) if the Purchase Contract Settlement Date has occurred,
         deliver the shares of Common Stock issuable in respect of the Purchase
         Contracts forming a part of the Securities evidenced by such other
         Certificate; or

                  (ii) if a Termination Event shall have occurred prior to the
         Purchase Contract Settlement Date, transfer the Preferred Securities,
         the Senior Deferrable Notes, the Treasury Securities, or the
         appropriate Applicable Ownership Interest of the Treasury Portfolio, as
         the case may be, evidenced thereby, in each case subject to the
         applicable conditions and in accordance with the applicable provisions
         of Article Five hereof.

         SECTION 3.06. Book-entry Interests.

         The Certificates, on original issuance, will be issued in the form of
one or more fully registered Global Certificates, to be delivered to the
Depositary or its custodian by, or on behalf of, the Company. The Company hereby
designates DTC as the initial Depositary. Such Global Certificates shall
initially be registered on the books and records of the Company in the name of
Cede & Co., the nominee of the Depositary, and no Beneficial Owner will receive
a definitive Certificate representing such Beneficial Owner's interest in such
Global Certificate, except as provided in Section 3.09. The Purchase Contract
Agent shall enter into an agreement with the Depositary if so requested by the
Company. Unless and until definitive, fully registered Certificates have been
issued to Beneficial Owners pursuant to Section 3.09:

                  (i) the provisions of this Section 3.06 shall be in full force
         and effect;

                  (ii) the Company shall be entitled to deal with the Depositary
         for all purposes of this Agreement (including receiving approvals,
         votes or consents hereunder) as the Holder of the Securities and the
         sole holder of the Global Certificates and shall have no obligation to
         the Beneficial Owners;

                  (iii) to the extent that the provisions of this Section 3.06
         conflict with any other provisions of this Agreement, the provisions of
         this Section 3.06 shall control; and

                  (iv) the rights of the Beneficial Owners shall be exercised
         only through the Depositary and shall be limited to those established
         by law and agreements between such Beneficial Owners and the Depositary
         or the Depositary Participants.

         SECTION 3.07.  Notices to Holders.

         Whenever a notice or other communication to the Holders is required to
be given under this Agreement, the Company or the Company's agent shall give
such notices and communications to the Holders and, with respect to any
Securities registered in the name of the

                                       22
<PAGE>   27

Depositary or the nominee of the Depositary, the Company or the Company's agent
shall, except as set forth herein, have no obligations to the Beneficial Owners.

         SECTION 3.08. Appointment of Successor Depositary.

         If the Depositary elects to discontinue its services as securities
depositary with respect to the Securities, the Company may, in its sole
discretion, appoint a successor Depositary with respect to the Securities.

         SECTION 3.09. Definitive Certificates.

         If:

                  (i) the Depositary elects to discontinue its services as
         securities depositary with respect to the Securities and a successor
         Depositary is not appointed within 90 days after such discontinuance
         pursuant to Section 3.08; or

                  (ii) the Company elects after consultation with the Purchase
         Contract Agent to terminate the book-entry system for the Securities,

then (x) definitive Certificates shall be prepared by the Company with respect
to such Securities and delivered to the Purchase Contract Agent and (y) upon
surrender of the Global Certificates representing the Securities by the
Depositary, accompanied by registration instructions, the Company shall cause
definitive Certificates to be delivered to Beneficial Owners in accordance with
the instructions of the Depositary. The Company shall not be liable for any
delay in delivery of such instructions and may conclusively rely on and shall be
protected in relying on, such instructions. Each definitive Certificate so
delivered shall evidence Securities of the same kind and tenor as the Global
Certificate so surrendered in respect thereof.

         SECTION 3.10. Mutilated, Destroyed, Lost and Stolen Certificates.

         If any mutilated Certificate is surrendered to the Purchase Contract
Agent, the Company shall execute and deliver to the Purchase Contract Agent, and
the Purchase Contract Agent shall authenticate, execute on behalf of the Holder,
and deliver in exchange therefor, a new Certificate, evidencing the same number
of PEPS Units or Treasury PEPS Units, as the case may be, and bearing a
Certificate number not contemporaneously outstanding.

         If there shall be delivered to the Company and the Purchase Contract
Agent (i) evidence to their satisfaction of the destruction, loss or theft of
any Certificate, and (ii) such security or indemnity as may be required by them
to hold each of them and any agent of any of them harmless, then, in the absence
of notice to the Company or the Purchase Contract Agent that such Certificate
has been acquired by a bona fide purchaser, the Company shall execute and
deliver to the Purchase Contract Agent, and the Purchase Contract Agent shall
authenticate, execute on

                                       23
<PAGE>   28

behalf of the Holder, and deliver to the Holder, in lieu of any such destroyed,
lost or stolen Certificate, a new Certificate, evidencing the same number of
PEPS Units or Treasury PEPS Units, as the case may be, and bearing a Certificate
number not contemporaneously outstanding.

         Notwithstanding the foregoing, the Company shall not be obligated to
execute and deliver to the Purchase Contract Agent, and the Purchase Contract
Agent shall not be obligated to authenticate, execute on behalf of the Holder,
and deliver to the Holder, a Certificate on or after the Business Day
immediately preceding the earlier of the Purchase Contract Settlement Date or
the Termination Date. In lieu of delivery of a new Certificate, upon
satisfaction of the applicable conditions specified above in this Section and
receipt of appropriate registration or transfer instructions from such Holder,
the Purchase Contract Agent shall:

                  (i) if the Purchase Contract Settlement Date has occurred,
         deliver the shares of Common Stock issuable in respect of the Purchase
         Contracts forming a part of the Securities evidenced by such
         Certificate; or

                  (ii) if a Termination Event shall have occurred prior to the
         Purchase Contract Settlement Date, transfer the Preferred Securities,
         the Senior Deferrable Notes, the Treasury Securities or the appropriate
         Applicable Ownership Interest (as specified in clause (A) of the
         definition of such term) of the Treasury Portfolio, as the case may be,
         evidenced thereby, in each case subject to the applicable conditions
         and in accordance with the applicable provisions of Article Five
         hereof.

         Upon the issuance of any new Certificate under this Section, the
Company and the Purchase Contract Agent may require the payment by the Holder of
a sum sufficient to cover any tax or other governmental charge that may be
imposed in relation thereto and any other expenses (including the fees and
expenses of the Purchase Contract Agent) connected therewith.

         Every new Certificate issued pursuant to this Section in lieu of any
destroyed, lost or stolen Certificate shall constitute an original additional
contractual obligation of the Company and of the Holder in respect of the
Security evidenced thereby, whether or not the destroyed, lost or stolen
Certificate (and the Securities evidenced thereby) shall be at any time
enforceable by anyone, and shall be entitled to all the benefits and be subject
to all the obligations of this Agreement equally and proportionately with any
and all other Certificates delivered hereunder.

         The provisions of this Section are exclusive and shall preclude, to the
extent lawful, all other rights and remedies with respect to the replacement or
payment of mutilated, destroyed, lost or stolen Certificates.

         SECTION 3.11. Persons Deemed Owners.

         Prior to due presentment of a Certificate for registration of transfer,
the Company and the Purchase Contract Agent, and any agent of the Company or the
Purchase Contract Agent, may

                                       24
<PAGE>   29

treat the Person in whose name such Certificate is registered as the owner of
the Security evidenced thereby, for the purpose of receiving distributions on
the Preferred Securities, the Treasury Securities, the Senior Deferrable Notes,
or on the maturing quarterly interest strips of the Treasury Portfolio, as
applicable, performance of the Purchase Contracts and for all other purposes
whatsoever, whether or not any distributions on the Preferred Securities, the
Treasury Securities, the Senior Deferrable Notes, or Treasury Portfolio, as
applicable, constituting a part of the Security evidenced thereby shall be
overdue and notwithstanding any notice to the contrary, and neither the Company
nor the Purchase Contract Agent, nor any agent of the Company or the Purchase
Contract Agent, shall be affected by notice to the contrary.

         Notwithstanding the foregoing, with respect to any Global Certificate,
nothing contained herein shall prevent the Company, the Purchase Contract Agent
or any agent of the Company or the Purchase Contract Agent, from giving effect
to any written certification, proxy or other authorization furnished by the
Depositary (or its nominee), as a Holder, with respect to such Global
Certificate or impair, as between such Depositary and the related Beneficial
Owner, the operation of customary practices governing the exercise of rights of
the Depositary (or its nominee) as Holder of such Global Certificate.

         SECTION 3.12. Cancellation.

         All Certificates surrendered for delivery of shares of Common Stock on
or after the Purchase Contract Settlement Date, upon the transfer of Preferred
Securities, Senior Deferrable Notes, the appropriate Applicable Ownership
Interest (as specified in clause (A) of the definition of that term) of the
Treasury Portfolio or Treasury Securities, as the case may be, after the
occurrence of a Termination Event or pursuant to an Early Settlement, or upon
the registration of transfer or exchange of a Security, or a Collateral
Substitution or the reestablishment of PEPS Units shall, if surrendered to any
Person other than the Purchase Contract Agent, be delivered to the Purchase
Contract Agent and, if not already cancelled, shall be promptly cancelled by it.
The Company may at any time deliver to the Purchase Contract Agent for
cancellation any Certificates previously authenticated, executed and delivered
hereunder which the Company may have acquired in any manner whatsoever, and all
Certificates so delivered shall, upon Issuer Order, be promptly cancelled by the
Purchase Contract Agent. No Certificates shall be authenticated, executed on
behalf of the Holder and delivered in lieu of or in exchange for any
Certificates cancelled as provided in this Section, except as expressly
permitted by this Agreement. All cancelled Certificates held by the Purchase
Contract Agent shall be disposed of in accordance with its customary practices.

         If the Company or any Affiliate of the Company shall acquire any
Certificate, such acquisition shall not operate as a cancellation of such
Certificate unless and until such Certificate is delivered to the Purchase
Contract Agent cancelled or for cancellation.

                                       25
<PAGE>   30

         SECTION 3.13. Creation of Treasury Peps Units by Substitution of
Treasury Securities.

         Subject to the conditions set forth in this Agreement, a Holder may
separate the Preferred Securities or the Senior Deferrable Notes, as applicable,
from the related Purchase Contracts in respect of such Holder's PEPS Units by
substituting for such Preferred Securities or Senior Deferrable Notes, as
applicable, Treasury Securities in an aggregate principal amount equal to the
aggregate liquidation amount of such Preferred Securities or the aggregate
principal amount of such Senior Deferrable Notes, as applicable (a "COLLATERAL
SUBSTITUTION"), at any time from and after the date of this Agreement and prior
to or on the seventh Business Day immediately preceding August 18, 2003. To
effect such substitution, the Holder must:

          (1)   deposit with the Securities Intermediary Treasury Securities
                having an aggregate principal amount equal to the aggregate
                liquidation amount of the Preferred Securities or the aggregate
                principal amount of the Senior Deferrable Notes comprising part
                of such PEPS Units, as the case may be; and

          (2)   transfer the related PEPS Units to the Purchase Contract Agent
                accompanied by a notice to the Purchase Contract Agent,
                substantially in the form of Exhibit C hereto, (i) stating that
                the Holder has transferred the relevant amount of Treasury
                Securities to the Securities Intermediary and (ii) requesting
                that the Purchase Contract Agent instruct the Collateral Agent
                to release the Preferred Securities or the Senior Deferrable
                Notes, as the case may be, underlying such PEPS Units, whereupon
                the Purchase Contract Agent shall promptly provide an
                instruction to such effect to the Collateral Agent,
                substantially in the form of Exhibit A to the Pledge Agreement.

         Upon receipt of the Treasury Securities described in clause (1) above
and the instruction described in clause (2) above, in accordance with the terms
of the Pledge Agreement, the Collateral Agent will cause the Securities
Intermediary to effect the release of such Preferred Securities or the Senior
Deferrable Notes, as the case may be, from the Pledge, free and clear of the
Company's security interest therein, and the transfer of such Preferred
Securities or the Senior Deferrable Notes, as the case may be, to the Purchase
Contract Agent on behalf of the Holder. Upon receipt thereof, the Purchase
Contract Agent shall promptly:

                  (i) cancel the related PEPS Units;

                  (ii) transfer the Preferred Securities or the Senior
         Deferrable Notes, as the case may be, to the Holder; and

                  (iii) authenticate, execute on behalf of such Holder and
         deliver a Treasury PEPS Units Certificate executed by the Company in
         accordance with Section 3.03 evidencing the same number of Purchase
         Contracts as were evidenced by the cancelled PEPS Units.

                                       26
<PAGE>   31

         Holders who elect to separate the Preferred Securities or the Senior
Deferrable Notes, as the case may be, from the related Purchase Contracts and to
substitute Treasury Securities for such Preferred Securities or the Senior
Deferrable Notes, as the case may be, shall be responsible for any fees or
expenses payable to the Collateral Agent for its services as Collateral Agent in
respect of the substitution, and the Company shall not be responsible for any
such fees or expenses.

         Holders may make Collateral Substitutions only in integral multiples of
40 PEPS Units. If a Tax Event Redemption has occurred, Holders may no longer
convert their PEPS Units into Treasury PEPS Units.

         In the event a Holder making a Collateral Substitution pursuant to this
Section 3.13 fails to effect a book-entry transfer of the PEPS Units or fails to
deliver PEPS Units Certificates to the Purchase Contract Agent after depositing
Treasury Securities with the Collateral Agent, any distributions on the
Preferred Securities or the Senior Deferrable Notes constituting a part of such
PEPS Units, as the case may be, shall be held in the name of the Purchase
Contract Agent or its nominee in trust for the benefit of such Holder, until
such PEPS Units are so transferred or the PEPS Units Certificate is so
delivered, as the case may be, or, such Holder provides evidence satisfactory to
the Company and the Purchase Contract Agent that such PEPS Units Certificate has
been destroyed, lost or stolen, together with any indemnity that may be required
by the Purchase Contract Agent and the Company.

         Except as described in this Section 3.13, for so long as the Purchase
Contract underlying a PEPS Unit remains in effect, such PEPS Unit shall not be
separable into its constituent parts, and the rights and obligations of the
Holder in respect of the Preferred Securities or the Senior Deferrable Notes, as
the case may be, and the Purchase Contract comprising such PEPS Unit may be
acquired, and may be transferred and exchanged, only as a PEPS Unit.

         SECTION 3.14. Reestablishment of Peps Units.

         Subject to the conditions set forth in this Agreement, a Holder of
Treasury PEPS Units may reestablish PEPS Units at any time (i) prior to or on
the seventh Business Day immediately preceding August 18, 2003, by:

          (1)   depositing with the Securities Intermediary Preferred Securities
                or Senior Deferrable Notes, as the case may be, having an
                aggregate liquidation amount (in the case of Preferred
                Securities) or aggregate principal amount (in the case of Senior
                Deferrable Notes), as the case may be, equal to the aggregate
                principal amount at maturity of the Treasury Securities
                comprising part of the Treasury PEPS Units; and

                                       27
<PAGE>   32

          (2)   transferring the related Treasury PEPS Units to the Purchase
                Contract Agent accompanied by a notice to the Purchase Contract
                Agent, substantially in the form of Exhibit C hereto, (i)
                stating that the Holder has transferred the relevant amount of
                Preferred Securities or Senior Deferrable Notes, as the case may
                be, to the Securities Intermediary and (ii) requesting that the
                Purchase Contract Agent instruct the Collateral Agent to release
                the Treasury Securities underlying such Treasury PEPS Units,
                whereupon the Purchase Contract Agent shall promptly provide an
                instruction to such effect to the Collateral Agent,
                substantially in the form of Exhibit C to the Pledge Agreement.

Upon receipt of the Preferred Securities or the Senior Deferrable Notes, as the
case may be, described in clause (1) above and the instruction described in
clause (2) above, in accordance with the terms of the Pledge Agreement, the
Collateral Agent will cause the Securities Intermediary to effect the release of
the Treasury Securities having a corresponding aggregate principal amount at
maturity from the Pledge, free and clear of the Company's security interest
therein, and the transfer to the Purchase Contract Agent on behalf of the
Holder. Upon receipt thereof, the Purchase Contract Agent shall promptly:

                  (i) cancel the related Treasury PEPS Units;

                  (ii) transfer the Treasury Securities to the Holder; and

                  (iii) authenticate, execute on behalf of such Holder and
         deliver a PEPS Units Certificate executed by the Company in accordance
         with Section 3.03 evidencing the same number of Purchase Contracts as
         were evidenced by the cancelled Treasury PEPS Units.

         Holders who elect to reestablish PEPS Units shall be responsible for
any fees or expenses payable to the Collateral Agent for its services as
Collateral Agent in respect of the reestablishment, and the Company shall not be
responsible for any such fees or expenses.

         Holders of Treasury PEPS Units may only reestablish PEPS Units in
integral multiples of 40 Treasury PEPS Units. If a Tax Event Redemption has
occurred, Holders may no longer convert their Treasury PEPS Units into PEPS
Units.

         Except as provided in this Section 3.14, for so long as the Purchase
Contract underlying a Treasury PEPS Unit remains in effect, such Treasury PEPS
Unit shall not be separable into its constituent parts and the rights and
obligations of the Holder of such Treasury PEPS Unit in respect of the 1/40 of a
Treasury Security and the Purchase Contract comprising such Treasury PEPS Unit
may be acquired, and may be transferred and exchanged, only as a Treasury PEPS
Unit.

                                       28
<PAGE>   33

         SECTION 3.15. Transfer of Collateral upon Occurrence of Termination
Event.

         Upon the occurrence of a Termination Event and the transfer to the
Purchase Contract Agent of the Preferred Securities, Senior Deferrable Notes,
the appropriate Applicable Ownership Interest of the Treasury Portfolio or the
Treasury Securities, as the case may be, underlying the PEPS Units and the
Treasury PEPS Units, as the case may be, pursuant to the terms of the Pledge
Agreement, the Purchase Contract Agent shall request transfer instructions with
respect to such Preferred Securities, Senior Deferrable Notes, the appropriate
Applicable Ownership Interest of the Treasury Portfolio or Treasury Securities,
as the case may be, from each Holder by written request, substantially in the
form of Exhibit D hereto, mailed to such Holder at its address as it appears in
the Security Register.

         Upon book-entry transfer of the PEPS Units or the Treasury PEPS Units
or delivery of a PEPS Units Certificate or Treasury PEPS Units Certificate to
the Purchase Contract Agent with such transfer instructions, the Purchase
Contract Agent shall transfer the Preferred Securities, Senior Deferrable Notes,
the appropriate Applicable Ownership Interest of the Treasury Portfolio or
Treasury Securities, as the case may be, underlying such PEPS Units or Treasury
PEPS Units, as the case may be, to such Holder by book-entry transfer, or other
appropriate procedures, in accordance with such instructions. In the event a
Holder of PEPS Units or Treasury PEPS Units fails to effect such transfer or
delivery, the Preferred Securities, Senior Deferrable Notes, the appropriate
Applicable Ownership Interest of the Treasury Portfolio or Treasury Securities,
as the case may be, underlying such PEPS Units or Treasury PEPS Units, as the
case may be, and any distributions thereon, shall be held in the name of the
Purchase Contract Agent or its nominee in trust for the benefit of such Holder,
until the earlier to occur of:

                  (i) the transfer of such PEPS Units or Treasury PEPS Units or
         surrender of the PEPS Units Certificate or Treasury PEPS Units
         Certificate or receipt by the Company and the Purchase Contract Agent
         from such Holder of satisfactory evidence that such PEPS Units
         Certificate or Treasury PEPS Units Certificate has been destroyed, lost
         or stolen, together with any indemnity that may be required by the
         Purchase Contract Agent and the Company; and

                  (ii) the expiration of the time period specified in the
         abandoned property laws of the relevant State.

         SECTION 3.16. No Consent to Assumption.

         Each Holder of a Security, by acceptance thereof, shall be deemed
expressly to have withheld any consent to the assumption under Section 365 of
the Bankruptcy Code or otherwise, of the Purchase Contract by the Company or its
trustee, receiver, liquidator or a person or entity performing similar functions
in the event that the Company becomes the debtor under the Bankruptcy Code or
subject to other similar state or Federal law providing for reorganization or
liquidation.

                                       29
<PAGE>   34

                                    ARTICLE 4
   THE PREFERRED SECURITIES, SENIOR DEFERRABLE NOTES AND APPLICABLE OWNERSHIP
                       INTEREST OF THE TREASURY PORTFOLIO

         SECTION 4.01. Interest Payments; Rights to Interest Payments Preserved.

         Any distribution on any Preferred Security, any Senior Deferrable Note
or on the appropriate Applicable Ownership Interest of the Treasury Portfolio,
as the case may be, which is paid on any Payment Date shall, subject to receipt
thereof by the Purchase Contract Agent from the Collateral Agent as provided by
the terms of the Pledge Agreement, be paid to the Person in whose name the PEPS
Units Certificate (or one or more Predecessor PEPS Units Certificates) of which
such Preferred Security, such Senior Deferrable Note or the appropriate
Applicable Ownership Interest of the Treasury Portfolio, as the case may be, is
registered at the close of business on the Record Date for such Payment Date.

         Each PEPS Units Certificate evidencing Preferred Securities, Senior
Deferrable Notes or the appropriate Applicable Ownership Interest of the
Treasury Portfolio delivered under this Agreement upon registration of transfer
of or in exchange for or in lieu of any other PEPS Units Certificate shall carry
the right to distributions accrued and unpaid, and to accrue distributions
interest, which were carried by the Preferred Securities, Senior Deferrable
Notes or the appropriate Applicable Ownership Interest of the Treasury Portfolio
underlying such other PEPS Units Certificate.

         In the case of any PEPS Units with respect to which Cash Settlement of
the underlying Purchase Contract is properly effected pursuant to Section 5.02
hereof, or with respect to which Early Settlement of the underlying Purchase
Contract is properly effected pursuant to Section 5.07 hereof, or with respect
to which a Collateral Substitution is effected, in each case on a date that is
after any Record Date and prior to or on the next succeeding Payment Date,
distributions on the Preferred Securities, Senior Deferrable Notes or on the
appropriate Applicable Ownership Interest of the Treasury Portfolio, as the case
may be, underlying such PEPS Unit otherwise payable on such Payment Date shall
be payable on such Payment Date notwithstanding such Cash Settlement or Early
Settlement or Collateral Substitution, and such distributions shall, subject to
receipt thereof by the Purchase Contract Agent, be payable to the Person in
whose name the PEPS Units Certificate (or one or more Predecessor PEPS Units
Certificates) was registered at the close of business on the Record Date. Except
as otherwise expressly provided in the immediately preceding sentence, in the
case of any PEPS Unit with respect to which Cash Settlement or Early Settlement
of the underlying Purchase Contract is properly effected, or with respect to
which a Collateral Substitution has been effected, distributions on the related
Preferred Securities, Senior Deferrable Notes or the appropriate Applicable
Ownership Interest of the Treasury Portfolio, as the case may be, that would
otherwise be payable after the Purchase Contract Settlement Date or Early
Settlement Date shall not be payable hereunder to the Holder of such PEPS Units;
provided, however, that to the extent that such Holder continues to hold
separated Preferred Securities or Senior Deferrable Notes that formerly
comprised a part of such

                                       30
<PAGE>   35

Holder's PEPS Unit, such Holder shall be entitled to receive distributions on
such separated Preferred Securities or Senior Deferrable Notes.

         Not later than 15 calendar days nor more than 30 calendar days prior to
the Remarketing Date, the Company shall request the Depositary to notify the
Beneficial Owners or Depositary Participants holding Securities of the
procedures to be followed by Holders of Securities who intend to effect a Cash
Settlement.

         SECTION 4.02. Notice and Voting.

         Under the terms of the Pledge Agreement, the Purchase Contract Agent
will be entitled to exercise the voting and any other consensual rights
pertaining to the Pledged Preferred Securities or Pledged Senior Deferrable
Notes, but only to the extent instructed in writing by the Holders as described
below. Upon receipt of notice of any meeting at which holders of Preferred
Securities or Senior Deferrable Notes are entitled to vote or upon any
solicitation of consents, waivers or proxies of holders of Preferred Securities
or Senior Deferrable Notes, the Purchase Contract Agent shall, as soon as
practicable thereafter, mail, first class, postage pre-paid, to the Holders of
PEPS Units a notice:

                  (i) containing such information as is contained in the notice
         or solicitation;

                  (ii) stating that each Holder on the record date set by the
         Purchase Contract Agent therefor (which, to the extent possible, shall
         be the same date as the record date for determining the holders of
         Preferred Securities or Senior Deferrable Notes, as the case may be,
         entitled to vote) shall be entitled to instruct the Purchase Contract
         Agent as to the exercise of the voting rights pertaining to such
         Preferred Securities or Senior Deferrable Notes underlying their PEPS
         Units; and

                  (iii) stating the manner in which such instructions may be
         given.

Upon the written request of the Holders of PEPS Units on such record date
received by the Purchase Contract Agent at least six days prior to such meeting,
the Purchase Contract Agent shall endeavor insofar as practicable to vote or
cause to be voted, in accordance with the instructions set forth in such
requests, the maximum number of Preferred Securities or Senior Deferrable Notes,
as the case may be, as to which any particular voting instructions are received.
In the absence of specific instructions from the Holder of a PEPS Unit, the
Purchase Contract Agent shall abstain from voting the Preferred Securities or
Senior Deferrable Notes underlying such PEPS Unit. The Company hereby agrees, if
applicable, to solicit Holders of PEPS Units to timely instruct the Purchase
Contract Agent in order to enable the Purchase Contract Agent to vote such
Preferred Securities or Senior Deferrable Notes and the Trust shall covenant to
this effect in the Declaration.

                                       31
<PAGE>   36

         SECTION 4.03. Distribution of Senior Deferrable Notes; Tax Event
Redemption.

         Upon the dissolution and liquidation of the Trust in accordance with
the Declaration, a principal amount at maturity of Senior Deferrable Notes
constituting the assets of the Trust and underlying the Preferred Securities
equal to the aggregate liquidation amount of the Pledged Preferred Securities
shall be delivered to the Securities Intermediary in exchange for the Pledged
Preferred Securities. Thereafter, the Senior Deferrable Notes will be
substituted for the Pledged Preferred Securities as the Collateral, and will be
held by the Securities Intermediary in the Collateral Account in accordance with
the terms of the Pledge Agreement to secure the obligations of each Holder of a
PEPS Unit to purchase the Common Stock of the Company under the Purchase
Contracts constituting a part of such PEPS Unit. Following the dissolution and
liquidation of the Trust, the Holders and the Collateral Agent shall have such
security interests, rights and obligations with respect to the Senior Deferrable
Notes as the Holders and the Collateral Agent had in respect of the Preferred
Securities subject to the Pledge thereof as provided in the Pledge Agreement.
The Company may cause to be made in any PEPS Unit Certificates thereafter to be
issued such change in phraseology and form (but not in substance) as may be
appropriate to reflect the dissolution and liquidation of the Trust and the
substitution of Senior Deferrable Notes for Preferred Securities as Collateral.

         Upon the occurrence of a Tax Event Redemption prior to the Purchase
Contract Settlement Date, the Redemption Price payable on the Tax Event
Redemption Date with respect to the Applicable Principal Amount shall be
deposited in the Collateral Account in exchange for the Pledged Preferred
Securities or the Pledged Senior Deferrable Notes. Thereafter, pursuant to the
terms of the Pledge Agreement, the Collateral Agent shall cause the Securities
Intermediary to apply an amount equal to the Redemption Amount of such
Redemption Price to purchase on behalf of the Holders of PEPS Units the Treasury
Portfolio and promptly remit the remaining portion of such Redemption Price to
the Purchase Contract Agent for payment to the Holders of such PEPS Units. The
Applicable Ownership Interest (as specified in clause (A) of the definition of
such term) of the Treasury Portfolio will be substituted as Collateral for the
Pledged Preferred Securities or the Pledged Senior Deferrable Notes, as the case
may be, and will be held by the Collateral Agent in accordance with the terms of
the Pledge Agreement to secure the obligation of each Holder of a PEPS Unit to
purchase the Common Stock of the Company under the Purchase Contract
constituting a part of such PEPS Unit. Following the occurrence of a Tax Event
Redemption prior to the Purchase Contract Settlement Date, the Holders of PEPS
Units and the Collateral Agent shall have such security interest rights and
obligations with respect to the Applicable Ownership Interest (as specified in
clause (A) of the definition of such term) of the Treasury Portfolio as the
Holders of PEPS Units and the Collateral Agent had in respect of the Preferred
Securities or Senior Deferrable Notes, as the case may be, subject to the Pledge
thereof as provided in the Pledge Agreement, and any reference herein to the
Preferred Securities or the Senior Deferrable Notes shall be deemed to be
reference to such Treasury Portfolio. The Company may cause to be made in any
PEPS Unit Certificates thereafter to be issued such change in phraseology and
form (but not in substance) as may be appropriate to reflect the liquidation of
the Trust and the substitution of the Applicable Ownership Interest (as
specified in

                                       32
<PAGE>   37

clause (A) of the definition of such term) of the Treasury Portfolio for
Preferred Securities or Senior Deferrable Notes as Collateral.

                                    ARTICLE 5
                             THE PURCHASE CONTRACTS

         SECTION 5.01. Purchase of Shares of Common Stock.

         Each Purchase Contract shall, unless a Cash Settlement has occurred in
accordance with Section 5.02 hereof or an Early Settlement has occurred in
accordance with Section 5.07 hereof, obligate the Holder of the related Security
to purchase, and the Company to sell, on the Purchase Contract Settlement Date
at a price equal to the Stated Amount (the "PURCHASE PRICE"), a number of shares
of Common Stock (subject to Section 5.09) equal to the Settlement Rate unless,
prior to or on the Purchase Contract Settlement Date, there shall have occurred
a Termination Event with respect to the Security of which such Purchase Contract
is a part. The "SETTLEMENT RATE" is equal to:

                  (i) if the Applicable Market Value (as defined below) is
         greater than or equal to $34.95 (the "THRESHOLD APPRECIATION PRICE"),
         .71531 shares of Common Stock per Purchase Contract;

                  (ii) if the Applicable Market Value is less than the Threshold
         Appreciation Price but greater than $29.125 (the "REFERENCE PRICE"),
         the number of shares of Common Stock per Purchase Contract having a
         value, based on the Applicable Market Value, equal to the Stated
         Amount; and

                  (iii) if the Applicable Market Value is less than or equal to
         the Reference Price, .85837 shares of Common Stock per Purchase
         Contract,

in each case subject to adjustment as provided in Section 5.04 (and in each case
rounded upward or downward to the nearest 1/10,000th of a share).

         The "APPLICABLE MARKET VALUE" means the average of the Closing Price
per share of Common Stock on each of the 20 consecutive Trading Days ending on
the third Trading Day immediately preceding the Purchase Contract Settlement
Date.

         The "CLOSING PRICE" per share of Common Stock on any date of
determination means:

                  (i) the closing sale price as of the 4:15 p.m. close of
         trading (or, if no closing price is reported, the last reported sale
         price) per share on the New York Stock Exchange, Inc. (the "NYSE") on
         such date;

                                       33
<PAGE>   38

                  (ii) if the Common Stock is not listed for trading on the NYSE
         on any such date, the closing sale price per share as reported in the
         composite transactions for the principal United States securities
         exchange on which the Common Stock is so listed;

                  (iii) if the Common Stock is not so listed on a United States
         national or regional securities exchange, the closing sale price per
         share as reported by The NASDAQ Stock Market, Inc.;

                  (iv) if the Common Stock is not so reported, the last quoted
         bid price for the Common Stock in the over-the-counter market as
         reported by the National Quotation Bureau or similar organization; or

                  (v) if such bid price is not available, the average of the
         mid-point of the last bid and ask prices of the Common Stock on such
         date from at least three nationally recognized independent investment
         banking firms retained for this purpose by the Company.

         A "TRADING DAY" means a day on which the Common Stock (1) is not
suspended from trading on any national or regional securities exchange or
association or over-the-counter market at the close of business and (2) has
traded at least once on the national or regional securities exchange or
association or over-the-counter market that is the primary market for the
trading of the Common Stock.

         Each Holder of a PEPS Unit or a Treasury PEPS Unit, by its acceptance
thereof:

                  (i) irrevocably authorizes the Purchase Contract Agent to
         enter into and perform the related Purchase Contract on its behalf as
         its attorney-in-fact (including the execution of Certificates on behalf
         of such Holder);

                  (ii) agrees to be bound by the terms and provisions thereof;

                  (iii) covenants and agrees to perform its obligations under
         such Purchase Contracts;

                  (iv) consents to the provisions hereof;

                  (v) irrevocably authorizes the Purchase Contract Agent to
         enter into and perform this Agreement and the Pledge Agreement on its
         behalf as its attorney-in-fact; and

                  (vi) consents to, and agrees to be bound by, the Pledge of the
         Preferred Securities, Senior Deferrable Notes, the Applicable Ownership
         Interest (as specified in

                                       34
<PAGE>   39

         clause (A) of the definition of such term) of the Treasury Portfolio or
         the Treasury Securities pursuant to the Pledge Agreement,

provided that upon a Termination Event, the rights of the Holder of such
Security under the Purchase Contract may be enforced without regard to any other
rights or obligations. Each Holder of a PEPS Unit or a Treasury PEPS Unit, by
its acceptance thereof, further covenants and agrees, that to the extent and in
the manner provided in Section 5.02 and the Pledge Agreement, but subject to the
terms thereof, payments in respect of the Preferred Securities or the Senior
Deferrable Notes or the proceeds from the Treasury Securities or the Applicable
Ownership Interest (as specified in clause (A) of the definition of such term)
of the Treasury Portfolio at maturity on the Purchase Contract Settlement Date,
as the case may be, shall be paid by the Collateral Agent to the Company in
satisfaction of such Holder's obligations under such Purchase Contract and such
Holder shall acquire no right, title or interest in such payments.

         Upon registration of transfer of a Certificate, the transferee shall be
bound (without the necessity of any other action on the part of such transferee)
by the terms of this Agreement, the Purchase Contracts underlying such
Certificate, the Declaration and the Pledge Agreement and the transferor shall
be released from the obligations under this Agreement, the Purchase Contracts
underlying the Certificate so transferred and the Pledge Agreement. The Company
covenants and agrees, and each Holder of a Certificate, by its acceptance
thereof, likewise covenants and agrees, to be bound by the provisions of this
paragraph.

         SECTION 5.02. Payment of Purchase Price.

         (a) (i) Unless a Tax Event Redemption has occurred or a Holder of a
PEPS Unit effects an Early Settlement of the underlying Purchase Contract in the
manner described in Section 5.07, each Holder who intends to pay in cash to
satisfy such Holder's obligations under the Purchase Contract shall notify the
Purchase Contract Agent by use of a notice in substantially the form of Exhibit
E hereto of his intention to pay in cash ("CASH SETTLEMENT") the Purchase Price
for the shares of Common Stock to be purchased pursuant to the related Purchase
Contract. Such notice shall be given prior to 5:00 p.m. (New York City time) on
the seventh Business Day immediately preceding August 18, 2003. Prior to 11:00
a.m. (New York City time) on the next succeeding Business Day, the Purchase
Contract Agent shall notify the Collateral Agent and the Indenture Trustee of
the receipt of such notices from Holders intending to make a Cash Settlement.

                  (ii) A Holder of a PEPS Unit who has so notified the Purchase
         Contract Agent of his intention to effect a Cash Settlement in
         accordance with paragraph 5.02(a)(i) above shall pay the Purchase Price
         to the Securities Intermediary for deposit in the Collateral Account
         prior to 11:00 a.m. (New York City time) on the fifth Business Day
         immediately preceding August 18, 2003, in lawful money of the United
         States by certified or cashiers' check or wire transfer, in each case
         in immediately available funds payable to or upon the order of the
         Securities Intermediary. Any cash received by the Collateral Agent
         shall be invested promptly by the Securities Intermediary in Permitted
         Investments and paid to the

                                       35
<PAGE>   40

         Company on the Purchase Contract Settlement Date in settlement of the
         Purchase Contracts in accordance with the terms of this Agreement and
         the Pledge Agreement. Any funds received by the Securities Intermediary
         in respect of the investment earnings from such Permitted Investments
         in excess of the Purchase Price for the shares of Common Stock to be
         purchased by such Holder shall be distributed to the Purchase Contract
         Agent when received for payment to the Holder.

                  (iii) If a Holder of a PEPS Unit fails to notify the Purchase
         Contract Agent of his intention to make a Cash Settlement in accordance
         with paragraph 5.02(a)(i) above, or does notify the Purchase Contract
         Agent as provided in paragraph 5.02(a)(i) above of his intention to pay
         the Purchase Price in cash, but fails to make such payment as required
         by paragraph 5.02(a)(ii) above, such Holder shall be deemed to have
         consented to the disposition of the Pledged Preferred Securities or the
         Pledged Senior Deferrable Notes pursuant to the Remarketing as
         described in paragraph 5.02(b) below.

                  (iv) Promptly after 11:00 a.m. (New York City time) on the
         fifth Business Day preceding the Purchase Contract Settlement Date, the
         Purchase Contract Agent, based on notices received by the Purchase
         Contract Agent pursuant to Section 5.02(a) hereof and notice from the
         Securities Intermediary regarding cash received by it prior to such
         time, shall notify the Collateral Agent and the Property Trustee of the
         aggregate number of Preferred Securities or Senior Deferrable Notes to
         be tendered for purchase in the Remarketing in a notice substantially
         in the form of Exhibit F hereto.

         (b) In order to dispose of the Preferred Securities or Senior
Deferrable Notes, PEPS Units Holders who have not notified the Purchase Contract
Agent of their intention to effect a Cash Settlement as provided in paragraph
5.02(a)(i) above, or who have so notified the Purchase Contract Agent but failed
to make such payment as required by paragraph 5.02(a)(ii) above, the Company
shall engage Morgan Stanley & Co. Incorporated, as Remarketing Agent (the
"REMARKETING AGENT"), pursuant to the Remarketing Agreement to sell such
Preferred Securities or Senior Deferrable Notes. In order to facilitate the
Remarketing, the Purchase Contract Agent, based on the notices specified in
Section 5.02(a)(iv), shall notify the Remarketing Agent, promptly after 11:00
a.m. (New York City time) on the fifth Business Day immediately preceding August
18, 2003, of the aggregate number of Preferred Securities or Senior Deferrable
Notes that are part of PEPS Units to be remarketed. Concurrently, the Collateral
Agent, pursuant to the terms of the Pledge Agreement, shall cause such Preferred
Securities or Senior Deferrable Notes to be presented to the Remarketing Agent
for Remarketing.

         Upon receipt of such notice from the Purchase Contract Agent and such
Preferred Securities or Senior Deferrable Notes, the Remarketing Agent shall, on
the third Business Day immediately preceding August 18, 2003, use reasonable
efforts to remarket such Preferred Securities or Senior Deferrable Notes on such
date at a price equal to 100.25% of the Stated Amount ($25.0625) per Preferred
Security or Senior Deferrable Note, as provided in the Remarketing Agreement.
The proceeds from the Remarketing shall be invested by the Collateral

                                       36
<PAGE>   41

Agent in Permitted Investments, in accordance with the Pledge Agreement, and
then applied to satisfy in full such PEPS Units Holders' obligations to pay the
Purchase Price for the shares of Common Stock under the related Purchase
Contracts on the Purchase Contract Settlement Date. In addition, $.0625 per
Preferred Security or Senior Deferrable Note of the proceeds shall automatically
be remitted to the Remarketing Agent for services rendered in connection with
the Remarketing (the "REMARKETING FEE").

         If, in spite of using its reasonable efforts, the Remarketing Agent
cannot remarket the related Preferred Securities or Senior Deferrable Notes of
such Holders of PEPS Units at a price equal to 100.25% of the Stated amount
($25.0625), then the Remarketing Agent shall increase the distribution rate on
the Preferred Securities or the interest rate on the Senior Deferrable Notes, as
the case may be, so that the market value of such Preferred Securities will
equal $25.0625. If the Remarketing Agent determines that it will be able to
remarket the related Preferred Securities or Senior Deferrable Notes of such
Holders of PEPS Units at a price in excess of 100.25% of the Stated Amount
($25.0625), then the Remarketing Agent shall decrease the distribution rate on
the Preferred Securities or the interest rate on the Senior Deferrable Notes, as
the case may be, so that the market value of such Preferred Securities or Senior
Deferrable Notes will be equal to $25.0625. If the Remarketing Agent cannot
Remarket the Preferred Securities or the Senior Deferrable Notes, as the case
may be, after such increase or decrease, the Remarketing shall be deemed to have
failed (a "FAILED REMARKETING"), an event of default shall be deemed to have
occurred under this Agreement and the Pledge Agreement and in accordance with
the terms of the Pledge Agreement, the Collateral Agent, for the benefit of the
Company, shall exercise its rights as a secured party with respect to such
Preferred Securities or Senior Deferrable Notes, including those actions
specified in paragraph 5.02(c) below; provided, that if upon a Failed
Remarketing the Collateral Agent exercises such rights for the benefit of the
Company with respect to such Preferred Securities or Senior Deferrable Notes,
any accrued and unpaid distributions on such Preferred Securities or Senior
Deferrable Notes shall become payable by the Company to the Purchase Contract
Agent for payment to the Beneficial Owner of the PEPS Units to which such
Preferred Securities or Senior Deferrable Notes relate. The Company shall cause
a notice of such Failed Remarketing to be published on the second Business Day
immediately preceding the Purchase Contract Settlement Date in a daily newspaper
in the English language of general circulation in the City of New York, which is
expected to be The Wall Street Journal, and on Bloomberg News.

         (c) With respect to any Preferred Securities or Senior Deferrable Notes
which are subject to a Failed Remarketing, the Collateral Agent for the benefit
of the Company reserves all of its rights as a secured party with respect
thereto and, subject to applicable law and paragraph 5.02(g) below, may, among
other things, (i) retain the Preferred Securities or Senior Deferrable Notes in
full satisfaction of the Holders' obligations under the Purchase Contracts or
(ii) sell the Preferred Securities or Senior Deferrable Notes in one or more
public or private sales.

         (d) (i) Unless a Holder of a Treasury PEPS Units or PEPS Units (if a
Tax Event Redemption has occurred) effects an Early Settlement of the underlying
Purchase Contract

                                       37
<PAGE>   42

through the early delivery of cash to the Purchase Contract Agent in the manner
described in Section 5.07, each Holder of a Treasury PEPS Unit or PEPS Unit (if
a Tax Event Redemption has occurred) who intends to pay in cash shall notify the
Purchase Contract Agent by use of a notice in substantially the form of Exhibit
E hereto of his intention to pay in cash the Purchase Price for the shares of
Common Stock to be purchased pursuant to the related Purchase Contract. Such
notice shall be given prior to 5:00 p.m. (New York City time) on the second
Business Day immediately preceding August 18, 2003. Prior to 11:00 a.m. (New
York City time) on the next succeeding Business Day, the Purchase Contract Agent
shall notify the Collateral Agent of the receipt of such notices from such
Holders intending to make a Cash Settlement. Treasury PEPS Unit holders may make
Cash Settlements only in integral multiples of 40 Treasury PEPS Units.

                  (ii) A Holder of a Treasury PEPS Unit or PEPS Units (if a Tax
         Event Redemption has occurred) who has so notified the Purchase
         Contract Agent of his intention to make a Cash Settlement in accordance
         with paragraph 5.02(d)(i) above shall pay the Purchase Price to the
         Securities Intermediary for deposit in the Collateral Account prior to
         11:00 a.m. (New York City time) on the Business Day immediately
         preceding August 18, 2003, in lawful money of the United States by
         certified or cashiers' check or wire transfer, in each case in
         immediately available funds payable to or upon the order of the
         Securities Intermediary. Any cash received by the Collateral Agent
         shall be invested promptly by the Securities Intermediary in Permitted
         Investments and paid to the Company on the Purchase Contract Settlement
         Date in settlement of the Purchase Contract in accordance with the
         terms of this Agreement and the Pledge Agreement. Any funds received by
         the Securities Intermediary in respect of the investment earnings from
         the investment in such Permitted Investments in excess of the Purchase
         Price for the shares of common stock to be purchased by such Holder
         shall be distributed to the Purchase Contract Agent when received for
         payment to the Holder.

                  (iii) If a Holder of a Treasury PEPS Unit or Holder of a PEPS
         Unit (if a Tax Event Redemption has occurred) fails to notify the
         Purchase Contract Agent of his intention to make a Cash Settlement in
         accordance with paragraph 5.02(d)(i) above, or does notify the Purchase
         Contract Agent as provided in paragraph 5.02(d)(i) above of his
         intention to pay the Purchase Price in cash, but fails to make such
         payment as required by paragraph 5.02(d)(ii) above, then upon the
         maturity of the Pledged Treasury Securities or the appropriate
         Applicable Ownership Interest (as specified in clause (A) of the
         definition of such term) of the Treasury Portfolio held by the
         Securities Intermediary on the Business Day immediately preceding the
         Purchase Contract Settlement Date, the principal amount of the Treasury
         Securities or the appropriate Applicable Ownership Interest (as
         specified in clause (A) of the definition of such term) of the Treasury
         Portfolio received by the Securities Intermediary shall be invested
         promptly in Permitted Investments. On the Purchase Contract Settlement
         Date, an amount equal to the Purchase Price shall be remitted to the
         Company as payment thereof without receiving any instructions from the
         Holder. In the event the sum of the proceeds from the related Pledged
         Treasury Securities or the appropriate Applicable Ownership Interest
         (as

                                       38
<PAGE>   43

         specified in clause (A) of the definition of such term) of the Treasury
         Portfolio and the investment earnings earned from such investments is
         in excess of the aggregate Purchase Price of the Purchase Contracts
         being settled thereby, the Collateral Agent shall cause the Securities
         Intermediary to distribute such excess to the Purchase Contract Agent
         for the benefit of the Holder of the related Treasury PEPS Unit or PEPS
         Unit when received.

                  (iv) A holder of a Preferred Security or Senior Deferred Note
         that is no longer part of a PEPS Unit may elect to have such Preferred
         Security or Senior Deferrable Note, as the case may be, remarketed. A
         holder making such an election must notify the Property Trustee prior
         to 11:00 a.m. (New York City time) on the fifth Business Day
         immediately preceding August 18, 2003, of the aggregate number of
         Preferred Securities or Senior Deferrable Notes, as the case may be,
         that are not part of PEPS Units to be remarketed. Any such notice will
         be irrevocable and may not be conditioned upon the level at which the
         Reset Rate is established in the Remarketing. Concurrently, the
         Property Trustee shall cause such Preferred Securities or Senior
         Deferrable Notes, as the case may be, to be presented to the
         Remarketing Agent for Remarketing.

         (e) Any distribution to Holders of excess funds described above shall
be payable at the office of the Purchase Contract Agent in New York City
maintained for that purpose or, at the option of the Holder, by check mailed to
the address of the Person entitled thereto at such address as it appears on the
Security Register.

         (f) Upon Cash Settlement of any Purchase Contract:

                  (i) the Collateral Agent will in accordance with the terms of
         the Pledge Agreement cause the Pledged Preferred Securities, Pledged
         Senior Deferrable Notes, the appropriate Applicable Ownership Interest
         (as specified in clause (A) of the definition of such term) of the
         Treasury Portfolio or the Pledged Treasury Securities, as the case may
         be, underlying the relevant Security to be released from the Pledge,
         free and clear of any security interest of the Company, and transferred
         to the Purchase Contract Agent for delivery to the Holder thereof or
         its designee as soon as practicable; and

                  (ii) subject to the receipt thereof, the Purchase Contract
         Agent shall, by book-entry transfer or other appropriate procedures, in
         accordance with written instructions provided by the Holder thereof,
         transfer such Preferred Securities, Senior Deferrable Notes, or the
         appropriate Applicable Ownership Interest (as specified in clause (A)
         of the definition of such term) of the Treasury Portfolio or such
         Treasury Securities, as the case may be (or, if no such instructions
         are given to the Purchase Contract Agent by the Holder, the Purchase
         Contract Agent shall hold such Preferred Securities, Senior Deferrable
         Notes, or the appropriate Applicable Ownership Interest (as specified
         in clause (A) of the definition of such term) of the Treasury Portfolio
         or such Treasury Securities, as the case may be, and any interest
         payment thereon, in the name of the Purchase Contract Agent or its
         nominee in trust for the benefit of such Holder until the expiration of
         the time period specified in the abandoned property laws of the
         relevant state).

                                       39
<PAGE>   44

         (g) The obligations of the Holders to pay the Purchase Price are
non-recourse obligations and, except to the extent satisfied by Early Settlement
or Cash Settlement, are payable solely out of the proceeds of any Collateral
pledged to secure the obligations of the Holders and in no event will Holders be
liable for any deficiency between the proceeds of the disposition of Collateral
and the Purchase Price.

         (h) The Company shall not be obligated to issue any shares of Common
Stock in respect of a Purchase Contract or deliver any certificates thereof to
the Holder of the related Security unless the Company shall have received
payment in full for the aggregate purchase price for the Common Stock to be
purchased thereunder in the manner herein set forth.

         SECTION 5.03. Issuance of Shares of Common Stock.

         Unless a Termination Event or an Early Settlement shall have occurred,
subject to Section 5.04(b), on the Purchase Contract Settlement Date upon
receipt of the aggregate Purchase Price payable on all Outstanding Securities,
the Company shall issue and deposit with the Purchase Contract Agent, for the
benefit of the Holders of the Outstanding Securities, one or more certificates
representing the shares of Common Stock registered in the name of the Purchase
Contract Agent (or its nominee) as custodian for the Holders (such certificates
for shares of Common Stock, together with any dividends or distributions for
which a record date and payment date for such dividend or distribution has
occurred after the Purchase Contract Settlement Date, being hereinafter referred
to as the "PURCHASE CONTRACT SETTLEMENT FUND") to which the Holders are entitled
hereunder.

         Subject to the foregoing, upon surrender of a Certificate to the
Purchase Contract Agent on or after the Purchase Contract Settlement Date,
together with settlement instructions thereon duly completed and executed, the
Holder of such Certificate shall be entitled to receive forthwith in exchange
therefor a certificate representing that number of whole shares of Common Stock
which such Holder is entitled to receive pursuant to the provisions of this
Article Five (after taking into account all Securities then held by such
Holder), together with cash in lieu of fractional shares as provided in Section
5.09 and any dividends or distributions with respect to such shares constituting
part of the Purchase Contract Settlement Fund, but without any interest thereon,
and the Certificate so surrendered shall forthwith be cancelled. Such shares
shall be registered in the name of the Holder or the Holder's designee as
specified in the settlement instructions provided by the Holder to the Purchase
Contract Agent. If any shares of Common Stock issued in respect of a Purchase
Contract are to be registered to a Person other than the Person in whose name
the Certificate evidencing such Purchase Contract is registered, no such
registration shall be made unless the Person requesting such registration has
paid any transfer and other taxes required by reason of such registration in a
name other than that of the registered Holder of the Certificate evidencing such
Purchase Contract or has established to the satisfaction of the Company that
such tax either has been paid or is not payable.

                                       40
<PAGE>   45

         SECTION 5.04. Adjustment of Settlement Rate.

         (a) Adjustments for Dividends, Distributions, Stock Splits, Etc.

         (1) In case the Company shall pay or make a dividend or other
distribution on Common Stock in Common Stock, the Settlement Rate in effect at
the opening of business on the day following the date fixed for the
determination of shareholders entitled to receive such dividend or other
distribution shall be increased by dividing such Settlement Rate by a fraction
of which:

                  (i) the numerator shall be the number of shares of Common
         Stock outstanding at the close of business on the date fixed for such
         determination; and

                  (ii) the denominator shall be the sum of such number of shares
         and the total number of shares constituting such dividend or other
         distribution,

such increase to become effective immediately after the opening of business on
the day following the date fixed for such determination. For the purposes of
this paragraph (1), the number of shares of Common Stock at any time outstanding
shall not include shares held in the treasury of the Company but shall include
any shares issuable in respect of any scrip certificates issued in lieu of
fractions of shares of Common Stock. The Company shall not pay any dividend or
make any distribution on shares of Common Stock held in the treasury of the
Company.

         (2) In case the Company shall issue rights, warrants or options to all
holders of its Common Stock (not being available on an equivalent basis to
Holders of the Securities upon settlement of the Purchase Contracts underlying
such Securities) entitling them, for a period expiring within 45 days after the
record date for the determination of shareholders entitled to receive such
rights, warrants or options, to subscribe for or purchase shares of Common Stock
at a price per share less than the Current Market Price per share of Common
Stock on the date fixed for the determination of shareholders entitled to
receive such rights, warrants or options the Settlement Rate in effect at the
opening of business on the day following the date fixed for such determination
shall be increased by dividing such Settlement Rate by a fraction of which:

                  (i) the numerator shall be the number of shares of Common
         Stock outstanding at the close of business on the date fixed for such
         determination plus the number of shares of Common Stock which the
         aggregate of the offering price of the total number of shares of Common
         Stock so offered for subscription or purchase would purchase at such
         Current Market Price; and

                  (ii) the denominator shall be the number of shares of Common
         Stock outstanding at the close of business on the date fixed for such
         determination plus the number of shares of Common Stock so offered for
         subscription or purchase,

                                       41
<PAGE>   46

such increase to become effective immediately after the opening of business on
the day following the date fixed for such determination. For the purposes of
this paragraph (2), the number of shares of Common Stock at any time outstanding
shall not include shares held in the treasury of the Company but shall include
any shares issuable in respect of any scrip certificates issued in lieu of
fractions of shares of Common Stock. The Company agrees that it shall not issue
any such rights, warrants or options in respect of shares of Common Stock held
in the treasury of the Company.

         (3) In case outstanding shares of Common Stock shall be subdivided or
split into a greater number of shares of Common Stock, the Settlement Rate in
effect at the opening of business on the day following the day upon which such
subdivision or split becomes effective shall be proportionately increased, and,
conversely, in case outstanding shares of Common Stock shall each be combined
into a smaller number of shares of Common Stock, the Settlement Rate in effect
at the opening of business on the day following the day upon which such
combination becomes effective shall be proportionately reduced, such increase or
reduction, as the case may be, to become effective immediately after the opening
of business on the day following the day upon which such subdivision, split or
combination becomes effective.

         (4) In case the Company shall, by dividend or otherwise, distribute to
all holders of its Common Stock evidences of its indebtedness or assets
(including securities, but excluding any rights, warrants or options referred to
in paragraph (2) of this Section 5.04(a), any dividend or distribution paid
exclusively in cash and any dividend or distribution referred to in paragraph
(1) of this Section 5.04(a)), the Settlement Rate shall be adjusted so that the
same shall equal the rate determined by dividing the Settlement Rate in effect
immediately prior to the close of business on the date fixed for the
determination of shareholders entitled to receive such distribution by a
fraction of which:

                  (i) the numerator shall be the Current Market Price per share
         of Common Stock on the date fixed for such determination less the then
         fair market value (as reasonably determined by the Board of Directors,
         whose determination shall be conclusive and the basis for which shall
         be described in a Board Resolution) of the portion of the assets or
         evidences of indebtedness so distributed applicable to one share of
         Common Stock; and

                  (ii) the denominator shall be such Current Market Price per
         share of Common Stock,

such adjustment to become effective immediately prior to the opening of business
on the day following the date fixed for the determination of shareholders
entitled to receive such distribution. In any case in which this paragraph (4)
is applicable, paragraph (2) of this Section 5.04(a) shall not be applicable. In
the event that such dividend or distribution is not so paid or made, the
Settlement Rate shall again be adjusted to be the Settlement Rate which would
then be in effect if such dividend or distribution had not been declared.

                                       42
<PAGE>   47

         (5) In case the Company shall, by dividend or otherwise, distribute to
all holders of its Common Stock cash (excluding:

                  (i) any quarterly cash dividend on Common Stock to the extent
         that the aggregate cash dividend per share of Common Stock in any
         fiscal quarter does not exceed $.08 per share (the "DIVIDEND
         THRESHOLD"), and

                  (ii) any dividend or distribution in connection with the
         liquidation, dissolution or termination of the Company, whether
         voluntary or involuntary),

then, in such case, the Settlement Rate shall be increased so that the same
shall equal the rate determined by dividing the Settlement Rate in effect
immediately prior to the close of business on such record date by a fraction of
which:

                  (i) the numerator shall be the Current Market Price of Common
         Stock on the record date less the amount of cash so distributed (and
         not excluded as provided above) applicable to one share of Common
         Stock; and

                  (ii) the denominator shall be the Current Market Price of
         Common Stock,

such increase to be effective immediately prior to the opening of business on
the day following the record date; provided, however, that in the event the
portion of cash so distributed applicable to one share of Common Stock is equal
to or greater than the Current Market Price per share of Common Stock on the
record date, in lieu of the foregoing adjustment, adequate provision shall be
made so that each holder of a Security shall have the right to receive upon
settlement of the Securities the amount of cash such Holder would have received
had such Holder settled each Security on the record date. In the event that such
dividend or distribution is not so paid or made, the Settlement Rate shall again
be adjusted to be the Settlement Rate which would then be in effect if such
dividend or distribution had not been declared. If any adjustment is required to
be made as set forth in this Section 5.04(a)(5) as a result of a distribution
that is a quarterly dividend, such adjustment shall be based upon the amount by
which such distribution exceeds the amount of the Dividend Threshold. If an
adjustment is required to be made as set forth in this Section 5.04(a)(5) above
as a result of a distribution that is not a quarterly dividend, such adjustment
shall be based upon the full amount of the distribution.

         (6) In case a tender or exchange offer made by the Company or any
subsidiary of the Company for all or any portion of Common Stock shall expire
and such tender or exchange offer (as amended upon the expiration thereof) shall
require the payment to shareholders (based on the acceptance (up to any maximum
specified in the terms of the tender or exchange offer) of Purchased Shares as
herein defined) of an aggregate consideration having a fair market value (as
reasonably determined by the Board of Directors, whose determination shall be
conclusive and the basis for which shall be described in a Board Resolution)
that combined together with the aggregate of the cash plus the fair market value
(as reasonably determined by the Board of

                                       43
<PAGE>   48

Directors, whose determination shall be conclusive and the basis for which shall
be described in a Board Resolution), as of the expiration of such tender or
exchange offer, of consideration payable in respect of any other tender or
exchange offer, by the Company or any subsidiary of the Company for all or any
portion of Common Stock expiring within the 12 months preceding the expiration
of such tender or exchange offer and in respect of which no adjustment pursuant
to this paragraph (6) has been made, and (II) the aggregate amount of any
distributions to all holders of Common Stock made exclusively in cash within the
12 months preceding the expiration of such tender or exchange offer and in
respect of which no adjustment pursuant to paragraph (6) has been made, exceeds
15% of the product of the Current Market Price per share of Common Stock as of
the last time (the "EXPIRATION TIME") tenders could have been made pursuant to
such tender or exchange offer (as it may be amended) times the number of shares
of Common Stock outstanding (including any tendered shares) on the Expiration
Time, then, and in each such case, immediately prior to the opening of business
on the day after the date of the Expiration Time, the Settlement Rate shall be
adjusted so that the same shall equal the rate determined by dividing the
Settlement Rate immediately prior to the close of business on the date of the
Expiration Time by a fraction:

                  (i) the numerator of which shall be equal to (A) the product
         of (I) the Current Market Price per share of Common Stock on the date
         of the Expiration Time and (II) the number of shares of Common Stock
         outstanding (including any tendered shares) on the Expiration Time less
         (B) the amount of cash plus the fair market value (determined as
         aforesaid) of the aggregate consideration payable to shareholders based
         on the transactions described in clauses (I) and (II) above (assuming
         in the case of clause (I) the acceptance, up to any maximum specified
         in the terms of the tender or exchange offer, of Purchased Shares); and

                  (ii) the denominator of which shall be equal to the product of
         (A) the Current Market Price per share of Common Stock as of the
         Expiration Time and (B) the number of shares of Common Stock
         outstanding (including any tendered shares) as of the Expiration Time
         less the number of all shares validly tendered and not withdrawn as of
         the Expiration Time (the shares deemed so accepted, up to any such
         maximum, being referred to as the "PURCHASED SHARES").

         (7) The reclassification of Common Stock into securities including
securities other than Common Stock (other than any reclassification upon a
Reorganization Event to which Section 5.04(b) applies) shall be deemed to
involve:

                  (i) a distribution of such securities other than Common Stock
         to all holders of Common Stock (and the effective date of such
         reclassification shall be deemed to be "the date fixed for the
         determination of shareholders entitled to receive such distribution"
         and the "date fixed for such determination" within the meaning of
         paragraph (4) of this Section); and

                                       44
<PAGE>   49

                  (ii) a subdivision, split or combination, as the case may be,
         of the number of shares of Common Stock outstanding immediately prior
         to such reclassification into the number of shares of Common Stock
         outstanding immediately thereafter (and the effective date of such
         reclassification shall be deemed to be "the day upon which such
         subdivision or split becomes effective" or "the day upon which such
         combination becomes effective", as the case may be, and "the day upon
         which such subdivision, split or combination becomes effective" within
         the meaning of paragraph (3) of this Section).

         (8) The "CURRENT MARKET PRICE" per share of Common Stock on any date of
determination means the average of the daily Closing Prices for the five
consecutive Trading Days selected by the Company commencing not more than 30
Trading Days before, and ending not later than, the earlier of such date of
determination and the day before the "ex date" with respect to the issuance or
distribution requiring such computation. For purposes of this paragraph, the
term "ex date," when used with respect to any issuance or distribution, shall
mean the first date on which Common Stock trades on such exchange or in such
market without the right to receive such issuance or distribution.

         (9) All adjustments to the Settlement Rate shall be calculated to the
nearest 1/10,000th of a share of Common Stock (or if there is not a nearest
1/10,000th of a share, to the next lower 1/10,000th of a share). No adjustment
in the Settlement Rate shall be required unless such adjustment would require an
increase or decrease of at least one percent thereof; provided, however, that
any adjustments which by reason of this subparagraph are not required to be made
shall be carried forward and taken into account in any subsequent adjustment. If
an adjustment is made to the Settlement Rate pursuant to paragraph (1), (2),
(3), (4), (5), (6), (7) or (10) of this Section 5.04(a), an adjustment shall
also be made to the Applicable Market Value solely to determine which of clauses
(i), (ii) or (iii) of the definition of Settlement Rate in Section 5.01 will
apply on the Purchase Contract Settlement Date. Such adjustment shall be made by
multiplying the Applicable Market Value by a fraction of which the numerator
shall be the Settlement Rate immediately after such adjustment pursuant to
paragraph (1), (2), (3), (4), (5), (6), (7) or (10) of this Section 5.04(a) and
the denominator shall be the Settlement Rate immediately prior to such
adjustment; provided, however, that if such adjustment to the Settlement Rate is
required to be made pursuant to the occurrence of any of the events contemplated
by paragraph (1), (2), (3), (4), (5), (6), (7) or (10) of this Section 5.04(a)
during the period taken into consideration for determining the Applicable Market
Value, appropriate and customary adjustments shall be made to the Settlement
Rate.

         (10) The Company may, but shall not be required to, make such increases
in the Settlement Rate, in addition to those required by this Section, as it
considers to be advisable in order to avoid or diminish any income tax to any
holders of shares of Common Stock resulting from any dividend or distribution of
stock or issuance of rights or warrants to purchase or subscribe for stock or
from any event treated as such for income tax purposes or for any other reason.

                                       45
<PAGE>   50

         (b) Adjustment for Consolidation, Merger or Other Reorganization Event.

         (1) In the event of:

                  (i) any consolidation or merger of the Company with or into
         another Person (other than a merger or consolidation in which the
         Company is the continuing corporation and in which the shares of Common
         Stock outstanding immediately prior to the merger or consolidation are
         not exchanged for cash, securities or other property of the Company or
         another corporation);

                  (ii) any sale, transfer, lease or conveyance to another Person
         of the property of the Company as an entirety or substantially as an
         entirety;

                  (iii) any statutory share exchange of the Company with another
         Person (other than in connection with a merger or acquisition);

                  (iv) any liquidation, dissolution or termination of the
         Company other than as a result of or after the occurrence of a
         Termination Event, (any such event, a "REORGANIZATION EVENT").

the Settlement Rate will be adjusted to provide that each Holder of Securities
will receive on the Purchase Contract Settlement Date with respect to each
Purchase Contract forming a part thereof, the kind and amount of securities,
cash and other property receivable upon such Reorganization Event (without any
interest thereon, and without any right to dividends or distribution thereon
which have a record date that is prior to the Purchase Contract Settlement Date)
by a Holder of the number of shares of Common Stock issuable on account of each
Purchase Contract if the Purchase Contract Settlement Date had occurred
immediately prior to such Reorganization Event, assuming such Holder of Common
Stock is not a Person with which the Company consolidated or into which the
Company merged or which merged into the Company or to which such sale or
transfer was made, as the case may be (any such Person, a "CONSTITUENT PERSON"),
or an Affiliate of a Constituent Person to the extent such Reorganization Event
provides for different treatment of Common Stock held by Affiliates of the
Company and non-affiliates and such Holder failed to exercise his rights of
election, if any, as to the kind or amount of securities, cash and other
property receivable upon such Reorganization Event (provided that if the kind or
amount of securities, cash and other property receivable upon such
Reorganization Event is not the same for each share of Common Stock held
immediately prior to such Reorganization Event by other than a Constituent
Person or an Affiliate thereof and in respect of which such rights of election
shall not have been exercised ("NON-ELECTING SHARE"), then for the purpose of
this Section the kind and amount of securities, cash and other property
receivable upon such Reorganization Event by each non-electing share shall be
deemed to be the kind and amount so receivable per share by a plurality of the
non-electing shares).

                                       46
<PAGE>   51

         In the event of such a Reorganization Event, the Person formed by such
consolidation, merger or exchange or the Person which acquires the assets of the
Company or, in the event of a liquidation, dissolution or termination of the
Company, the Company or a liquidating trust created in connection therewith,
shall execute and deliver to the Purchase Contract Agent an agreement
supplemental hereto providing that each Holder of an Outstanding Security shall
have the rights provided by this Section 5.04(b). Such supplemental agreement
shall provide for adjustments which, for events subsequent to the effective date
of such supplemental agreement, shall be as nearly equivalent as may be
practicable to the adjustments provided for in this Section. The above
provisions of this Section shall similarly apply to successive Reorganization
Events.

         (2) In the event of a consolidation or merger of the Company with or
into another Person, any merger of another Person into the Company (other than a
merger that does not result in any reclassification, conversion, exchange or
cancellation of outstanding shares of Common Stock) in which 30% or more of the
total consideration paid to the Company's shareholders consists of cash or cash
equivalents, then a Holder of a Security may settle his Purchase Contract for
cash as described in Section 5.02(a)(i) or 5.02(d)(i) hereof, as applicable,
during the one week period beginning on the twenty-third Trading Day following
the closing date of such merger (the "EARLY SETTLEMENT WEEK"), at the applicable
Settlement Rate. For the purposes of this Section, the twenty-third Trading Day
after the closing of the merger or consolidation shall be deemed to be the
Purchase Contract Settlement Date for the purpose of determining the Applicable
Market Value and the deadline for submitting the notice to settle early and the
related cash payment shall be 5:00 p.m. (New York City time) of the last
Business Day of the Early Settlement Week.

         (c) All calculations and determinations pursuant to this Section 5.04
shall be made by the Company or its agent and the Purchase Contract Agent shall
have no responsibility with respect thereto.

         SECTION 5.05. Notice of Adjustments and Certain Other Events.

         (a) Whenever the Settlement Rate is adjusted as herein provided, the
Company shall:

                  (i) forthwith compute the adjusted Settlement Rate in
         accordance with Section 5.04 and prepare and transmit to the Purchase
         Contract Agent an Officers' Certificate setting forth the Settlement
         Rate, the method of calculation thereof in reasonable detail, and the
         facts requiring such adjustment and upon which such adjustment is
         based; and

                  (ii) within 10 Business Days following the occurrence of an
         event that requires an adjustment to the Settlement Rate pursuant to
         Section 5.04 (or if the Company is not aware of such occurrence, as
         soon as practicable after becoming so aware), provide a written notice
         to the Holders of the Securities of the occurrence of such event and a
         statement in reasonable detail setting forth the method by which the
         adjustment to the Settlement Rate was determined and setting forth the
         adjusted Settlement Rate.

                                       47
<PAGE>   52

          (b) The Purchase Contract Agent shall not at any time be under any
duty or responsibility to any Holder of Securities to determine whether any
facts exist which may require any adjustment of the Settlement Rate, or with
respect to the nature or extent or calculation of any such adjustment when made,
or with respect to the method employed in making the same. The Purchase Contract
Agent shall not be accountable with respect to the validity or value (or the
kind or amount) of any shares of Common Stock, or of any securities or property,
which may at the time be issued or delivered with respect to any Purchase
Contract; and the Purchase Contract Agent makes no representation with respect
thereto. The Purchase Contract Agent shall not be responsible for any failure of
the Company to issue, transfer or deliver any shares of Common Stock pursuant to
a Purchase Contract or to comply with any of the duties, responsibilities or
covenants of the Company contained in this Article.

         SECTION 5.06. Termination Event; Notice.

         The Purchase Contracts and all obligations and rights of the Company
and the Holders thereunder, and the rights and obligations of Holders to
purchase Common Stock, shall immediately and automatically terminate, without
the necessity of any notice or action by any Holder, the Purchase Contract Agent
or the Company, if, prior to or on the Purchase Contract Settlement Date, a
Termination Event shall have occurred.

         Upon and after the occurrence of a Termination Event, the Securities
shall thereafter represent the right to receive the Preferred Securities, the
Senior Deferrable Notes, the Treasury Securities or the appropriate Applicable
Ownership Interest of the Treasury Portfolio, as the case may be, forming part
of such Securities, in accordance with the provisions of Section 5.02 of the
Pledge Agreement. Upon the occurrence of a Termination Event, the Company shall
promptly but in no event later than two Business Days thereafter give written
notice to the Purchase Contract Agent, the Collateral Agent and the Holders, at
their addresses as they appear in the Security Register.

         SECTION 5.07. Early Settlement.

         (a) Subject to and upon compliance with the provisions of this Section
5.07, at the option of the Holder thereof, Purchase Contracts underlying
Securities may be settled early ("EARLY SETTLEMENT") on or prior to 5:00 p.m.
(New York City time) on the seventh Business Day immediately preceding the
Purchase Contract Settlement Date. Holders of Treasury PEPS Units may only
settle the related Purchase Contracts in integral multiples of 40 Purchase
Contracts. In order to exercise the right to effect Early Settlement with
respect to any Purchase Contracts, the Holder of the Certificate evidencing
Securities shall deliver to the Purchase Contract Agent at the Corporate Trust
Office an Election to Settle Early form (on the reverse side of the Certificate)
and any other documents requested by the Purchase Contract Agent and accompanied
by payment (payable to the Company in immediately available funds) in an amount
(the "EARLY SETTLEMENT AMOUNT") equal to the product of (A) the Stated Amount
times (B) the

                                       48
<PAGE>   53

number of Purchase Contracts with respect to which the Holder has elected to
effect Early Settlement.

Except as provided in the immediately preceding sentence, no payment shall be
made upon Early Settlement of any Purchase Contract on account of any dividends
on the Common Stock issued upon such Early Settlement. If the foregoing
requirements are first satisfied with respect to Purchase Contracts underlying
any Securities prior to or at 5:00 p.m. (New York City time) on a Business Day,
such day shall be the "EARLY SETTLEMENT DATE" with respect to such Securities
and if such requirements are first satisfied after 5:00 p.m. (New York City
time) on a Business Day or on a day that is not a Business Day, the "EARLY
SETTLEMENT DATE" with respect to such Securities shall be the next succeeding
Business Day.

         (b) Upon Early Settlement of Purchase Contracts by a Holder of the
related Securities, the Company shall issue, and the Holder shall be entitled to
receive .71531 shares of Common Stock on account of each Purchase Contract as to
which Early Settlement is effected (the "EARLY SETTLEMENT RATE"). The Early
Settlement Rate shall be adjusted in the same manner and at the same time as the
Settlement Rate is adjusted.

         (c) No later than the third Business Day after the applicable Early
Settlement Date, the Company shall cause:

                  (i) the shares of Common Stock issuable upon Early Settlement
         of Purchase Contracts to be issued and delivered, together with payment
         in lieu of any fraction of a share, as provided in Section 5.09; and

                  (ii) the related Preferred Securities, Senior Deferrable Notes
         or the appropriate Applicable Ownership Interest (as specified in
         clause (A) of the definition of such term) of the Treasury Portfolio,
         in the case of PEPS Units, or the related Treasury Securities or the
         appropriate Applicable Ownership Interest (as specified in clause (A)
         of the definition of such term) of the Treasury Portfolio, in the case
         of Treasury PEPS Units, to be released from the Pledge by the
         Collateral Agent and transferred, in each case, to the Purchase
         Contract Agent for delivery to the Holder thereof or its designee.

         (d) Upon Early Settlement of any Purchase Contracts, and subject to
receipt of shares of Common Stock from the Company and the Preferred Securities,
Senior Deferrable Notes, the appropriate Applicable Ownership Interest as
specified in clause (A) of the definition of such term) of the Treasury
Portfolio, or Treasury Securities, as the case may be, from the Securities
Intermediary, as applicable, the Purchase Contract Agent shall, in accordance
with the instructions provided by the Holder thereof on the Election to Settle
Early form (on the reverse of the Certificate evidencing the related
Securities):

                  (i) transfer to the Holder the Preferred Securities, Senior
         Deferrable Notes, the appropriate Applicable Ownership Interest (as
         specified in clause (A) of the definition of

                                       49
<PAGE>   54

         such term) of the Treasury Portfolio or Treasury Securities, as the
         case may be, forming a part of such Securities; and

                  (ii) deliver to the Holder a certificate or certificates for
         the full number of shares of Common Stock issuable upon such Early
         Settlement, together with payment in lieu of any fraction of a share,
         as provided in Section 5.09.

         (e) In the event that Early Settlement is effected with respect to
Purchase Contracts underlying less than all the Securities evidenced by a
Certificate, upon such Early Settlement the Company shall execute and the
Purchase Contract Agent shall authenticate, countersign and deliver to the
Holder thereof, at the expense of the Company, a Certificate evidencing the
Securities as to which Early Settlement was not effected.

         (f) A Holder of a Security who effects Early Settlement may elect to
have the Preferred Securities or Senior Deferrable Notes, as the case may be, no
longer a part of a PEPS Unit, or Treasury PEPS Unit, as the case may be,
remarketed. A Holder making such an election must notify the Property Trustee
prior to 11:00 a.m. (New York City time) on the fifth Business Day immediately
preceding August 18, 2003, of the aggregate number of Preferred Securities or
Senior Deferrable Notes that are not part of PEPS Units or Treasury PEPS Units,
as the case may be, to be remarketed. Any such notice will be irrevocable and
may not be conditioned upon the level at which the Reset Rate is established in
the Remarketing. Concurrently, the Property Trustee shall cause such Preferred
Securities or Senior Deferrable Notes, as the case may be, to be presented to
the Remarketing Agent for Remarketing.

         SECTION 5.08. Intentionally Omitted.

         SECTION 5.09. No Fractional Shares.

         No fractional shares or scrip representing fractional shares of Common
Stock shall be issued or delivered upon settlement on the Purchase Contract
Settlement Date or upon Early Settlement of any Purchase Contracts. If
Certificates evidencing more than one Purchase Contract shall be surrendered for
settlement at one time by the same Holder, the number of full shares of Common
Stock which shall be delivered upon settlement shall be computed on the basis of
the aggregate number of Purchase Contracts evidenced by the Certificates so
surrendered. Instead of any fractional share of Common Stock which would
otherwise be deliverable upon settlement of any Purchase Contracts on the
Purchase Contract Settlement Date or upon Early Settlement, the Company, through
the Purchase Contract Agent, shall make a cash payment in respect of such
fractional interest in an amount equal to the value of such fractional shares
times the Applicable Market Value. The Company shall provide the Purchase
Contract Agent from time to time with sufficient funds to permit the Purchase
Contract Agent to make all cash payments required by this Section 5.09 in a
timely manner.

                                       50
<PAGE>   55

         SECTION 5.10. Charges and Taxes.

         The Company will pay all stock transfer and similar taxes attributable
to the initial issuance and delivery of the shares of Common Stock pursuant to
the Purchase Contracts; provided, however, that the Company shall not be
required to pay any such tax or taxes which may be payable in respect of any
exchange of or substitution for a Certificate evidencing a Security or any
issuance of a share of Common Stock in a name other than that of the registered
Holder of a Certificate surrendered in respect of the Securities evidenced
thereby, other than in the name of the Purchase Contract Agent, as custodian for
such Holder, and the Company shall not be required to issue or deliver such
share certificates or Certificates unless or until the Person or Persons
requesting the transfer or issuance thereof shall have paid to the Company the
amount of such tax or shall have established to the satisfaction of the Company
that such tax has been paid.

                                    ARTICLE 6
                                    REMEDIES

         SECTION 6.01. Unconditional Right of Holders to Purchase Shares of
Common Stock.

         Each Holder of a Security shall have the right, which is absolute and
unconditional, to purchase shares of Common Stock pursuant to such Purchase
Contract and, in each such case, to institute suit for the enforcement of the
right to purchase shares of Common Stock, and such rights shall not be impaired
without the consent of such Holder.

         SECTION 6.02. Restoration of Rights and Remedies.

         If any Holder has instituted any proceeding to enforce any right or
remedy under this Agreement and such proceeding has been discontinued or
abandoned for any reason, or has been determined adversely to such Holder, then
and in every such case, subject to any determination in such proceeding, the
Company and such Holder shall be restored severally and respectively to their
former positions hereunder and thereafter all rights and remedies of such Holder
shall continue as though no such proceeding had been instituted.

         SECTION 6.03. Rights and Remedies Cumulative.

         Except as otherwise provided with respect to the replacement or payment
of mutilated, destroyed, lost or stolen Certificates in the last paragraph of
Section 3.10, no right or remedy herein conferred upon or reserved to the
Holders is intended to be exclusive of any other right or remedy, and every
right and remedy shall, to the extent permitted by law, be cumulative and in
addition to every other right and remedy given hereunder or now or hereafter
existing at law or in equity or otherwise. The assertion or employment of any
right or remedy hereunder, or otherwise,

                                       51
<PAGE>   56

shall not prevent the concurrent assertion or employment of any other
appropriate right or remedy.

         SECTION 6.04. Delay or Omission Not Waiver.

         No delay or omission of any Holder to exercise any right or remedy upon
a default shall impair any such right or remedy or constitute a waiver of any
such right. Every right and remedy given by this Article or by law to the
Holders may be exercised from time to time, and as often as may be deemed
expedient, by such Holders.

         SECTION 6.05. Undertaking for Costs.

         All parties to this Agreement agree, and each Holder of a Security, by
its acceptance of such Security shall be deemed to have agreed, that any court
may in its discretion require, in any suit for the enforcement of any right or
remedy under this Agreement, or in any suit against the Purchase Contract Agent
for any action taken, suffered or omitted by it as Purchase Contract Agent, the
filing by any party litigant in such suit of an undertaking to pay the costs of
such suit, and that such court may in its discretion assess reasonable costs,
including reasonable attorneys' fees and costs against any party litigant in
such suit, having due regard to the merits and good faith of the claims or
defenses made by such party litigant; provided that the provisions of this
Section shall not apply to any suit instituted by the Purchase Contract Agent,
to any suit instituted by any Holder, or group of Holders, holding in the
aggregate more than 10% of the Outstanding Securities, or to any suit instituted
by any Holder for the enforcement of distributions on any Preferred Securities
or interest on any Senior Deferrable Notes on or after the respective Payment
Date therefor in respect of any Security held by such Holder, or for enforcement
of the right to purchase shares of Common Stock under the Purchase Contracts
constituting part of any Security held by such Holder.

         SECTION 6.06. Waiver of Stay or Extension Laws.

         The Company covenants (to the extent that it may lawfully do so) that
it will not at any time insist upon, or plead, or in any manner whatsoever claim
or take the benefit or advantage of, any stay or extension law wherever enacted,
now or at any time hereafter in force, which may affect the covenants or the
performance of this Agreement; and the Company (to the extent that it may
lawfully do so) hereby expressly waives all benefit or advantage of any such law
and covenants that it will not hinder, delay or impede the execution of any
power herein granted to the Purchase Contract Agent or the Holders, but will
suffer and permit the execution of every such power as though no such law had
been enacted.

                                       52
<PAGE>   57

                                    ARTICLE 7
                           THE PURCHASE CONTRACT AGENT

         SECTION 7.01. Certain Duties and Responsibilities.

         (a) The Purchase Contract Agent:

         (1) undertakes to perform, with respect to the Securities, such duties
and only such duties as are specifically set forth in this Agreement and the
Pledge Agreement, and no implied covenants or obligations shall be read into
this Agreement or the Pledge Agreement against the Purchase Contract Agent; and

         (2) in the absence of bad faith or gross negligence on its part, may,
with respect to the Securities, conclusively rely, as to the truth of the
statements and the correctness of the opinions expressed therein, upon
certificates or opinions furnished to the Purchase Contract Agent and conforming
to the requirements of this Agreement or the Pledge Agreement, as applicable,
but in the case of any certificates or opinions which by any provision hereof
are specifically required to be furnished to the Purchase Contract Agent, the
Purchase Contract Agent shall be under a duty to examine the same to determine
whether or not they conform to the requirements of this Agreement or the Pledge
Agreement, as applicable (but need not confirm or investigate the accuracy of
the mathematical calculations or other facts stated therein).

         (b) No provision of this Agreement or the Pledge Agreement shall be
construed to relieve the Purchase Contract Agent from liability for its own
grossly negligent action, its own grossly negligent failure to act, or its own
willful misconduct, except that:

         (1) this Subsection shall not be construed to limit the effect of
Subsection (a) of this Section;

         (2) the Purchase Contract Agent shall not be liable for any error of
judgment made in good faith by a Responsible Officer, unless it shall be proved
that the Purchase Contract Agent was negligent in ascertaining the pertinent
facts; and

         (3) no provision of this Agreement or the Pledge Agreement shall
require the Purchase Contract Agent to expend or risk its own funds or otherwise
incur any financial liability in the performance of any of its duties hereunder,
or in the exercise of any of its rights or powers, if indemnity satisfactory to
the Purchase Contract Agent is not provided to it.

         (4) the Purchase Contract Agent 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 a majority in principal amount of the Outstanding
Securities.

                                       53
<PAGE>   58

         (c) Whether or not therein expressly so provided, every provision of
this Agreement and the Pledge Agreement relating to the conduct or affecting the
liability of or affording protection to the Purchase Contract Agent shall be
subject to the provisions of this Section.

         (d) The Purchase Contract Agent is authorized to execute and deliver
the Pledge Agreement in its capacity as Purchase Contract Agent.

         SECTION 7.02. Notice of Default.

         Within 30 days after the occurrence of any default by the Company
hereunder of which a Responsible Officer of the Purchase Contract Agent has
actual knowledge, the Purchase Contract Agent shall transmit by mail to the
Company and the Holders of Securities, as their names and addresses appear in
the Security Register, notice of such default hereunder, unless such default
shall have been cured or waived.

         SECTION 7.03. Certain Rights of Purchase Contract Agent.

         Subject to the provisions of Section 7.01:

         (1) the Purchase Contract Agent 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, Senior Note, note, other evidence of indebtedness or other
paper or document believed by it to be genuine and to have been signed or
presented by the proper party or parties;

         (2) any request or direction of the Company mentioned herein shall be
sufficiently evidenced by an Officers' Certificate, Issuer Order or Issuer
Request, and any resolution of the Board of Directors of the Company may be
sufficiently evidenced by a Board Resolution;

         (3) whenever in the administration of this Agreement or the Pledge
Agreement the Purchase Contract Agent shall deem it desirable that a matter be
proved or established prior to taking, suffering or omitting any action
hereunder, the Purchase Contract Agent (unless other evidence be herein
specifically prescribed) may, in the absence of bad faith on its part,
conclusively rely upon an Officers' Certificate of the Company;

         (4) the Purchase Contract Agent may consult with counsel of its
selection and the advice of such counsel or any Opinion of Counsel 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 reliance thereon;

         (5) the Purchase Contract Agent 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, debebture, note, other evidence of indebtedness or other paper or
document, but the Purchase Contract Agent, in its discretion, and at the expense
of the

                                       54
<PAGE>   59

Company, may make reasonable further inquiry or investigation into such facts or
matters related to the execution, delivery and performance of the Purchase
Contracts as it may see fit, and, if the Purchase Contract Agent shall determine
to make such further inquiry or investigation, it shall be given a reasonable
opportunity to examine the relevant books, records and premises of the Company,
personally or by agent or attorney and shall incur no liability or additional
liability of any kind by reason of such inquiry or investigation;

         (6) the Purchase Contract Agent may execute any of the powers hereunder
or perform any duties hereunder either directly or by or through agents or
attorneys or an Affiliate and the Purchase Contract Agent shall not be
responsible for any misconduct or negligence on the part of any agent or
attorney or an Affiliate appointed with due care by it hereunder;

         (7) the Purchase Contract Agent shall be under no obligation to
exercise any of the rights or powers vested in it by this Agreement at the
request or direction of any of the Holders pursuant to this Agreement, unless
such Holders shall have offered to the Purchase Contract Agent security or
indemnity satisfactory to the Purchase Contract Agent against the costs,
expenses and liabilities which might be incurred by it in compliance with such
request or direction;

         (8) the Purchase Contract Agent shall not be liable for any action
taken, suffered, or omitted to be taken by it in good faith and reasonably
believed by it to be authorized or within the discretion or rights or powers
conferred upon it by this Agreement;

         (9) the Purchase Contract Agent shall not be deemed to have notice of
any Default or Event of Default unless a Responsible Officer of the Purchase
Contract Agent has actual knowledge thereof or unless written notice of any
event which is in fact such a default is received by the Purchase Contract Agent
at the Corporate Trust Office of the Purchase Contract Agent, and such notice
references the Securities and this Agreement;

         (10) the Purchase Contract Agent may request that the Company deliver
an Officers' Certificate setting forth the names of individuals and/or titles of
officers authorized at such time to take specified actions pursuant to this
Agreement, which Officers' Certificate may be signed by any person authorized to
sign an Officers' Certificate, including any person specified as so authorized
in any such certificate previously delivered and not superseded; and

         (11) the rights, privileges, protections, immunities and benefits given
to the Purchase Contract Agent, including, without limitation, its right to be
indemnified, are extended to, and shall be enforceable by, the Purchase Contract
Agent in each of its capacities hereunder, and to each agent, custodian and
other Person employed to act hereunder.

                                       55
<PAGE>   60

         SECTION 7.04. Not Responsible for Recitals or Issuance of Securities.

         The recitals contained herein and in the Certificates shall be taken as
the statements of the Company, and the Purchase Contract Agent assumes no
responsibility for their accuracy. The Purchase Contract Agent makes no
representations as to the validity or sufficiency of either this Agreement or of
the Securities, or of the Pledge Agreement or the Pledge. The Purchase Contract
Agent shall not be accountable for the use or application by the Company of the
proceeds in respect of the Purchase Contracts.

         SECTION 7.05. May Hold Securities.

         Any Security Registrar or any other agent of the Company, or the
Purchase Contract Agent and its Affiliates, in their individual or any other
capacity, may become the owner or pledgee of Securities and may otherwise deal
with the Company, the Collateral Agent or any other Person with the same rights
it would have if it were not Security Registrar or such other agent, or the
Purchase Contract Agent. The Company may become the owner or pledgee of
Securities.

         SECTION 7.06. Money Held in Custody.

         Money held by the Purchase Contract Agent in custody hereunder need not
be segregated from the other funds except to the extent required by law or
provided herein. The Purchase Contract Agent shall be under no obligation to
invest or pay interest on any money received by it hereunder except as otherwise
provided hereunder agreed in writing with the Company.

         SECTION 7.07. Compensation and Reimbursement.

         The Company agrees:

         (1) to pay to the Purchase Contract Agent compensation for all services
rendered by it hereunder and under the Pledge Agreement as the Company and the
Purchase Contract Agent shall from time to time agree in writing;

         (2) except as otherwise expressly provided for herein, to reimburse the
Purchase Contract Agent upon its request for all reasonable expenses,
disbursements and advances incurred or made by the Purchase Contract Agent in
accordance with any provision of this Agreement and the Pledge Agreement
(including the reasonable compensation and the expenses and disbursements of its
agents and counsel), except any such expense, disbursement or advance as may be
attributable to its gross negligence or willful misconduct; and

         (3) to indemnify the Purchase Contract Agent and any predecessor
Purchase Contract Agent for, and to hold it harmless against, any loss,
liability or expense incurred without gross negligence or willful misconduct on
its part, arising out of or in connection with the acceptance

                                       56
<PAGE>   61

or administration of its duties hereunder, including the costs and expenses of
defending itself against any claim (whether asserted by the Company, a Holder or
any other person) or liability in connection with the exercise or performance of
any of its powers or duties hereunder.

         SECTION 7.08. Corporate Purchase Contract Agent Required; Eligibility.

         There shall at all times be a Purchase Contract Agent hereunder which
shall be a corporation organized and doing business under the laws of the United
States of America, any State thereof or the District of Columbia, authorized
under such laws to exercise corporate trust powers, having (or being a member of
a bank holding company having) a combined capital and surplus of at least
$50,000,000, subject to supervision or examination by Federal or State authority
and having a corporate trust office in the Borough of Manhattan, New York City,
if there be such a corporation in the Borough of Manhattan, New York City,
qualified and eligible under this Article and willing to act on reasonable
terms. If such corporation publishes reports of condition at least annually,
pursuant to law or to the requirements of said supervising or examining
authority, then for the purposes of this Section, the combined capital and
surplus of such corporation shall be deemed to be its combined capital and
surplus as set forth in its most recent report of condition so published. If at
any time the Purchase Contract Agent shall cease to be eligible in accordance
with the provisions of this Section, it shall resign immediately in the manner
and with the effect hereinafter specified in this Article.

         SECTION 7.09. Resignation and Removal; Appointment of Successor.

         (a) No resignation or removal of the Purchase Contract Agent and no
appointment of a successor Purchase Contract Agent pursuant to this Article
shall become effective until the acceptance of appointment by the successor
Purchase Contract Agent in accordance with the applicable requirements of
Section 7.10.

         (b) The Purchase Contract Agent may resign at any time by giving
written notice thereof to the Company 60 days prior to the effective date of
such resignation. If the instrument of acceptance by a successor Purchase
Contract Agent required by Section 7.10 shall not have been delivered to the
Purchase Contract Agent within 30 days after the giving of such notice of
resignation, the resigning Purchase Contract Agent may petition, at the expense
of the Company, any court of competent jurisdiction for the appointment of a
successor Purchase Contract Agent.

         (c) The Purchase Contract Agent may be removed at any time by Act of
the Holders of a majority in number of the Outstanding Securities delivered to
the Purchase Contract Agent and the Company.

         (d) If at any time:

                  (1) the Purchase Contract Agent fails to comply with Section
         310(b) of the TIA, as if the Purchase Contract Agent were an indenture
         trustee under an indenture qualified

                                       57
<PAGE>   62

         under the TIA, after written request therefor by the Company or by any
         Holder who has been a bona fide Holder of a Security for at least six
         months;

                  (2) the Purchase Contract Agent shall cease to be eligible
         under Section 7.08 and shall fail to resign after written request
         therefor by the Company or by any such Holder; or

                  (3) the Purchase Contract Agent shall become incapable of
         acting or shall be adjudged a bankrupt or insolvent or a receiver of
         the Purchase Contract Agent or of its property shall be appointed or
         any public officer shall take charge or control of the Purchase
         Contract Agent or of its property or affairs for the purpose of
         rehabilitation, conservation or liquidation,

         then, in any such case, (i) the Company by a Board Resolution may
remove the Purchase Contract Agent, or (ii) any Holder who has been a bona fide
Holder of a Security for at least six months may, on behalf of himself and all
others similarly situated, petition any court of competent jurisdiction for the
removal of the Purchase Contract Agent and the appointment of a successor
Purchase Contract Agent.

         (e) If the Purchase Contract Agent shall resign, be removed or become
incapable of acting, or if a vacancy shall occur in the office of Purchase
Contract Agent for any cause, the Company, by a Board Resolution, shall promptly
appoint a successor Purchase Contract Agent and shall comply with the applicable
requirements of Section 7.10. If no successor Purchase Contract Agent shall have
been so appointed by the Company and accepted appointment in the manner required
by Section 7.10, any Holder who has been a bona fide Holder of a Security for at
least six months, on behalf of itself and all others similarly situated, or the
Purchase Contract Agent may petition at the expense of the Company, any court of
competent jurisdiction for the appointment of a successor Purchase Contract
Agent.

         (f) The Company shall give, or shall cause such successor Purchase
Contract Agent to give, notice of each resignation and each removal of the
Purchase Contract Agent and each appointment of a successor Purchase Contract
Agent by mailing written notice of such event by first-class mail, postage
prepaid, to all Holders as their names and addresses appear in the applicable
Register. Each notice shall include the name of the successor Purchase Contract
Agent and the address of its Corporate Trust Office.

         SECTION 7.10. Acceptance of Appointment by Successor.

         (a) In case of the appointment hereunder of a successor Purchase
Contract Agent, every such successor Purchase Contract Agent so appointed shall
execute, acknowledge and deliver to the Company and to the retiring Purchase
Contract Agent an instrument accepting such appointment, and thereupon the
resignation or removal of the retiring Purchase Contract Agent shall become
effective and such successor Purchase Contract Agent, without any further act,
deed

                                       58
<PAGE>   63

or conveyance, shall become vested with all the rights, powers, agencies and
duties of the retiring Purchase Contract Agent; but, on the request of the
Company or the successor Purchase Contract Agent, such retiring Purchase
Contract Agent shall, upon payment of its charges, execute and deliver an
instrument transferring to such successor Purchase Contract Agent all the
rights, powers and trusts of the retiring Purchase Contract Agent and shall duly
assign, transfer and deliver to such successor Purchase Contract Agent all
property and money held by such retiring Purchase Contract Agent hereunder.

         (b) Upon request of any such successor Purchase Contract Agent, the
Company shall execute any and all instruments for more fully and certainly
vesting in and confirming to such successor Purchase Contract Agent all such
rights, powers and agencies referred to in paragraph 7.10(a) of this Section.

         (c) No successor Purchase Contract Agent shall accept its appointment
unless at the time of such acceptance such successor Purchase Contract Agent
shall be qualified and eligible under this Article.

         SECTION 7.11. Merger, Conversion, Consolidation or Succession to
Business.

         Any corporation into which the Purchase Contract Agent may be merged or
converted or with which it may be consolidated, or any corporation resulting
from any merger, conversion or consolidation to which the Purchase Contract
Agent shall be a party, or any corporation succeeding to all or substantially
all the corporate trust business of the Purchase Contract Agent, shall be the
successor of the Purchase Contract Agent hereunder, provided such corporation
shall be otherwise qualified and eligible under this Article, with the execution
or filing of any paper or any further act on the part of any of the parties
hereto. In case any Certificates shall have been authenticated and executed on
behalf of the Holders, but not delivered, by the Purchase Contract Agent then in
office, any successor by merger, conversion or consolidation to such Purchase
Contract Agent may adopt such authentication and execution and deliver the
Certificates so authenticated and executed with the same effect as if such
successor Purchase Contract Agent had itself authenticated and executed such
Securities.

         SECTION 7.12. Preservation of Information; Communications to Holders.

         (a) The Purchase Contract Agent shall preserve, in as current a form as
is reasonably practicable, the names and addresses of Holders received by the
Purchase Contract Agent in its capacity as Security Registrar.

         (b) If three or more Holders (herein referred to as "applicants") apply
in writing to the Purchase Contract Agent, and furnish to the Purchase Contract
Agent reasonable proof that each such applicant has owned a Security for a
period of at least six months preceding the date of such application, and such
application states that the applicants desire to communicate with other Holders
with respect to their rights under this Agreement or under the Securities and is

                                       59
<PAGE>   64

accompanied by a copy of the form of proxy or other communication which such
applicants propose to transmit, then the Purchase Contract Agent shall mail to
all the Holders copies of the form of proxy or other communication which is
specified in such request, with reasonable promptness after a tender to the
Purchase Contract Agent of the materials to be mailed and of payment, or
provision for the payment, of the reasonable expenses of such mailing.

         SECTION 7.13. No Obligations of Purchase Contract Agent.

         Except to the extent otherwise expressly provided in this Agreement,
the Purchase Contract Agent assumes no obligations and shall not be subject to
any liability under this Agreement, the Pledge Agreement or any Purchase
Contract in respect of the obligations of the Holder of any Security thereunder.
The Company agrees, and each Holder of a Certificate, by his acceptance thereof,
shall be deemed to have agreed, that the Purchase Contract Agent's execution of
the Certificates on behalf of the Holders shall be solely as agent and attorney-
in-fact for the Holders, and that the Purchase Contract Agent shall have no
obligation to perform such Purchase Contracts on behalf of the Holders, except
to the extent expressly provided in Article Five hereof. Anything contained in
this Agreement to the contrary notwithstanding, in no event shall the Purchase
Contract Agent or its officers, employees or agents be liable under this
Agreement to any third party for indirect, special, punitive, or consequential
loss or damage of any kind whatsoever, including lost profits, whether or not
the likelihood of such loss or damage was known to the Purchase Contract Agent,
incurred without any act or deed that is found to be attributable to gross
negligence or willful misconduct on the part of the Purchase Contract Agent.

         SECTION 7.14. Tax Compliance.

         (a) The Company and the Purchase Contract Agent will comply with all
applicable certification, information reporting and withholding (including
"backup" withholding) requirements imposed by applicable tax laws, regulations
or administrative practice with respect to (i) any payments made with respect to
the Securities or (ii) the issuance, delivery, holding, transfer, redemption or
exercise of rights under the Securities. Such compliance shall include, without
limitation, the preparation and timely filing of required returns and the timely
payment of all amounts required to be withheld to the appropriate taxing
authority or its designated agent.

         (b) The Purchase Contract Agent shall comply in accordance with the
terms hereof with any written direction received from the Company with respect
to the execution or certification of any required documentation and the
application of such requirements to particular payments or Holders or in other
particular circumstances, and may for purposes of this Agreement conclusively
rely on any such direction in accordance with the provisions of Section
7.01(a)(2) hereof.

         (c) The Purchase Contract Agent shall maintain all appropriate records
documenting compliance with such requirements, and shall make such records
available, on written request, to the Company or its authorized representative
within a reasonable period of time after receipt of such request.

                                       60
<PAGE>   65

                                    ARTICLE 8
                             SUPPLEMENTAL AGREEMENTS

         SECTION 8.01. Supplemental Agreements Without Consent of Holders.

         Without the consent of any Holders, the Company and the Purchase
Contract Agent, at any time and from time to time, may enter into one or more
agreements supplemental hereto, in form satisfactory to the Company and the
Purchase Contract Agent, to:

                  (1) evidence the succession of another Person to the Company,
         and the assumption by any such successor of the covenants of the
         Company herein and in the Certificates;

                  (2) evidence and provide for the acceptance of appointment
         hereunder by a successor Purchase Contract Agent;

                  (3) add to the covenants of the Company for the benefit of the
         Holders, or surrender any right or power herein conferred upon the
         Company;

                  (4) make provision with respect to the rights of Holders
         pursuant to the requirements of Section 5.04(b); or

                  (5) except as provided for in Section 5.04, cure any
         ambiguity, correct or supplement any provisions herein which may be
         inconsistent with any other provisions herein, or make any other
         provisions with respect to such matters or questions arising under this
         Agreement, provided such action shall not adversely affect the
         interests of the Holders.

         SECTION 8.02. Supplemental Agreements with Consent of Holders.

         With the consent of the Holders of not less than a majority of the
outstanding Securities voting together as one class, by Act of said Holders
delivered to the Company and the Purchase Contract Agent, the Company, when
authorized by a Board Resolution, and the Purchase Contract Agent may enter into
an agreement or agreements supplemental hereto for the purpose of modifying in
any manner the terms of the Purchase Contracts, or the provisions of this
Agreement or the rights of the Holders in respect of the Securities; provided,
however, that, except as contemplated herein, no such supplemental agreement
shall, without the unanimous consent of the Holders of each outstanding Purchase
Contract affected thereby,

                                       61
<PAGE>   66

                  (1) change any Payment Date;

                  (2) change the amount or the type of Collateral required to be
         Pledged to secure a Holder's obligations under the Purchase Contract,
         impair the right of the Holder of any Purchase Contract to receive
         distributions on the related Collateral (except for the rights of
         Holders of PEPS Units to substitute Treasury Securities for the Pledged
         Preferred Securities or Pledged Senior Deferrable Notes or the
         Applicable Ownership Interest of the Treasury Portfolio or the rights
         of Holders or Treasury PEPS Units to substitute Preferred Securities,
         Senior Deferrable Notes or the Applicable Ownership Interest of the
         Treasury Portfolio for the Pledged Treasury Securities) or otherwise
         adversely affect the Holder's rights in or to such Collateral or
         adversely alter the rights in or to such Collateral;

                  (3) impair the right to institute suit for the enforcement of
         any Purchase Contract;

                  (4) reduce the number of shares of Common Stock to be
         purchased pursuant to any Purchase Contract, increase the price to
         purchase shares of Common Stock upon settlement of any Purchase
         Contract or change the Purchase Contract Settlement Date; or

                  (5) reduce the percentage of the outstanding Purchase
         Contracts the consent of whose Holders is required for any such
         supplemental agreement;

provided that if any amendment or proposal referred to above would adversely
affect only the PEPS Units or the Treasury PEPS Units, then only the affected
class of Holders as of the record date for the Holders entitled to vote thereon
will be entitled to vote on such amendment or proposal, and such amendment or
proposal shall not be effective except with the consent of Holders of not less
than a majority of such class; and provided, further, that the unanimous consent
of the Holders of each outstanding Purchase Contract of such class affected
thereby shall be required to approve any amendment or proposal specified in
clauses (1) through (5) above.

         It shall not be necessary for any Act of Holders under this Section to
approve the particular form of any proposed supplemental agreement, but it shall
be sufficient if such Act shall approve the substance thereof.

         SECTION 8.03. Execution of Supplemental Agreements.

         In executing, or accepting the additional agencies created by, any
supplemental agreement permitted by this Article or the modifications thereby of
the agencies created by this Agreement, the Purchase Contract Agent shall be
provided, and (subject to Section 7.01) shall be fully protected in relying
upon, an Officers' Certificate and an Opinion of Counsel stating that the
execution of such supplemental agreement is authorized or permitted by this
Agreement. The Purchase Contract Agent may, but shall not be obligated to, enter
into any such supplemental agreement which affects the Purchase Contract Agent's
own rights, duties or immunities under this Agreement or otherwise.

                                       62
<PAGE>   67

         SECTION 8.04. Effect of Supplemental Agreements.

         Upon the execution of any supplemental agreement under this Article,
this Agreement shall be modified in accordance therewith, and such supplemental
agreement shall form a part of this Agreement for all purposes; and every Holder
of Certificates theretofore or thereafter authenticated, executed on behalf of
the Holders and delivered hereunder, shall be bound thereby.

         SECTION 8.05. Reference to Supplemental Agreements.

         Certificates authenticated, executed on behalf of the Holders and
delivered after the execution of any supplemental agreement pursuant to this
Article may, and shall if required by the Purchase Contract Agent, bear a
notation in form approved by the Purchase Contract Agent as to any matter
provided for in such supplemental agreement. If the Company shall so determine,
new Certificates so modified as to conform, in the opinion of the Purchase
Contract Agent and the Company, to any such supplemental agreement may be
prepared and executed by the Company and authenticated, executed on behalf of
the Holders and delivered by the Purchase Contract Agent in exchange for
outstanding Certificates.

                                    ARTICLE 9
            MERGER, CONSOLIDATION, SHARE EXCHANGE, SALE OR CONVEYANCE

         SECTION 9.01. Covenant Not to Merge, Consolidate, Enter into a Share
Exchange, Sell or Convey Property Except under Certain Conditions.

         The Company covenants that it will not merge, consolidate or enter into
a share exchange with any other Person or sell, assign, transfer, lease or
convey all or substantially all of its properties and assets to any Person or
group of affiliated Persons in one transaction or a series of related
transactions, unless:

                  (i) either the Company shall be the continuing corporation, or
         the successor (if other than the Company) shall be a corporation
         organized and existing under the laws of the United States of America
         or a State thereof or the District of Columbia and such corporation
         shall expressly assume all the obligations of the Company under the
         Purchase Contracts, this Agreement and the Pledge Agreement by one or
         more supplemental agreements in form reasonably satisfactory to the
         Purchase Contract Agent and the Collateral Agent, executed and
         delivered to the Purchase Contract Agent and the Collateral Agent by
         such corporation; and

                                       63
<PAGE>   68

                  (ii) the Company or such successor corporation, as the case
         may be, shall not, immediately after such merger, consolidation or
         share exchange, or such sale, assignment, transfer, lease or
         conveyance, be in default in the performance of any covenant or
         condition hereunder, under any of the Securities or under the Pledge
         Agreement.

         SECTION 9.02. Rights and Duties of Successor Corporation.

         In case of any such merger, consolidation, share exchange, sale,
assignment, transfer, lease or conveyance and upon any such assumption by a
successor corporation in accordance with Section 9.01, such successor
corporation shall succeed to and be substituted for the Company with the same
effect as if it had been named herein as the Company. Such successor corporation
thereupon may cause to be signed, and may issue either in its own name or in the
name of Valero Energy Corporation, any or all of the Certificates evidencing
Securities issuable hereunder which theretofore shall not have been signed by
the Company and delivered to the Purchase Contract Agent; and, upon the order of
such successor corporation, instead of the Company, and subject to all the
terms, conditions and limitations in this Agreement prescribed, the Purchase
Contract Agent shall authenticate and execute on behalf of the Holders and
deliver any Certificates which previously shall have been signed and delivered
by the officers of the Company to the Purchase Contract Agent for authentication
and execution, and any Certificate evidencing Securities which such successor
corporation thereafter shall cause to be signed and delivered to the Purchase
Contract Agent for that purpose. All the Certificates issued shall in all
respects have the same legal rank and benefit under this Agreement as the
Certificates theretofore or thereafter issued in accordance with the terms of
this Agreement as though all of such Certificates had been issued at the date of
the execution hereof.

         In case of any such merger, consolidation, share exchange, sale,
assignment, transfer, lease or conveyance such change in phraseology and form
(but not in substance) may be made in the Certificates evidencing Securities
thereafter to be issued as may be appropriate.

         SECTION 9.03. Officers' Certificate and Opinion of Counsel Given to
Purchase Contract Agent.

         The Purchase Contract Agent, subject to Sections 7.01 and 7.03, shall
receive an Officers' Certificate and an Opinion of Counsel as conclusive
evidence that any such merger, consolidation, share exchange, sale, assignment,
transfer, lease or conveyance, and any such assumption, complies with the
provisions of this Article and that all conditions precedent to the consummation
of any such merger, consolidation, share exchange, sale, assignment, transfer,
lease or conveyance have been met.

                                       64
<PAGE>   69

                                   ARTICLE 10
                                    COVENANTS

         SECTION 10.01. Performance under Purchase Contracts.

         The Company covenants and agrees for the benefit of the Holders from
time to time of the Securities that it will duly and punctually perform its
obligations under the Purchase Contracts in accordance with the terms of the
Purchase Contracts and this Agreement.

         SECTION 10.02. Maintenance of Office or Agency.

         The Company will maintain in the Borough of Manhattan, New York City an
office or agency where Certificates may be presented or surrendered for
acquisition of shares of Common Stock upon settlement of the Purchase Contracts
on the Purchase Contract Settlement Date or Early Settlement and for transfer of
Collateral upon occurrence of a Termination Event, where Certificates may be
surrendered for registration of transfer or exchange, for a Collateral
Substitution or reestablishment of PEPS Units and where notices and demands to
or upon the Company in respect of the Securities and this Agreement may be
served. The Company will give prompt written notice to the Purchase Contract
Agent of the location, and any change in the location, of such office or agency.
If at any time the Company shall fail to maintain any such required office or
agency or shall fail to furnish the Purchase Contract Agent with the address
thereof, such presentations, surrenders, notices and demands may be made or
served at the Corporate Trust Office, and the Company hereby appoints the
Purchase Contract Agent as its agent to receive all such presentations,
surrenders, notices and demands.

         The Company may also from time to time designate one or more other
offices or agencies where Certificates may be presented or surrendered for any
or all such purposes and may from time to time rescind such designations;
provided, however, that no such designation or rescission shall in any manner
relieve the Company of its obligation to maintain an office or agency in the
Borough of Manhattan, New York City for such purposes. The Company will give
prompt written notice to the Purchase Contract Agent of any such designation or
rescission and of any change in the location of any such other office or agency.
The Company hereby designates as the place of payment for the Securities the
Corporate Trust Office and appoints the Purchase Contract Agent at its Corporate
Trust Office as paying agent in such city.

         SECTION 10.03. Company to Reserve Common Stock.

         The Company shall at all times prior to the Purchase Contract
Settlement Date reserve and keep available, free from preemptive rights, out of
its authorized but unissued Common Stock the full number of shares of Common
Stock issuable against tender of payment in respect of all Purchase Contracts
constituting a part of the Securities evidenced by Outstanding Certificates.

                                       65
<PAGE>   70

         SECTION 10.04. Covenants as to Common Stock.

         The Company covenants that all shares of Common Stock which may be
issued against tender of payment in respect of any Purchase Contract
constituting a part of the Outstanding Securities will, upon issuance, be duly
authorized, validly issued, fully paid and nonassessable.

         SECTION 10.05. Statements of Officers of the Company as to Default.

         The Company will deliver to the Purchase Contract Agent, within 140
days after the end of each fiscal year of the Company (which as of the date
hereof is December 31) ending after the date hereof, an Officers' Certificate
(one of the signers of which shall be the principal executive officer, principal
financial officer or principal accounting officer of the Company), stating
whether or not to the knowledge of the signers thereof the Company is in default
in the performance and observance of any of the terms, provisions and conditions
hereof, and if the Company shall be in default, specifying all such defaults and
the nature and status thereof of which they may have knowledge.

         SECTION 10.06. ERISA.

         Each Holder from time to time of the Securities that is a Plan hereby
represents that its acquisition of the PEPS Units and the holding of the same
satisfies the applicable fiduciary requirements of ERISA and that it is entitled
to exemption relief from the prohibited transaction provisions of ERISA and the
Code in accordance with one or more prohibited transaction exemptions or
otherwise will not result in a nonexempt prohibited transaction.

         [SIGNATURES ON THE FOLLOWING PAGE]

                                       66
<PAGE>   71

         IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
duly executed as of the day and year first above written.

                                       VALERO ENERGY CORPORATION

                                       By:
                                          --------------------------------------
                                          Name: John D. Gibbons
                                          Title: Vice President and Chief
                                                 Financial Officer

                                       THE BANK OF NEW YORK,
                                       as Purchase Contract Agent

                                       By:
                                          --------------------------------------
                                          Name:
                                          Title:

                                       67
<PAGE>   72

                                                                       EXHIBIT A

                         FACE OF PEPS UNITS CERTIFICATE

         "THIS CERTIFICATE IS A GLOBAL CERTIFICATE WITHIN THE MEANING OF THE
PURCHASE CONTRACT AGREEMENT HEREINAFTER REFERRED TO AND IS REGISTERED IN THE
NAME OF THE DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION (THE "DEPOSITARY"),
OR A NOMINEE OF THE DEPOSITARY. THIS CERTIFICATE IS EXCHANGEABLE FOR
CERTIFICATES REGISTERED IN THE NAME OF A PERSON OTHER THAN THE DEPOSITARY OR ITS
NOMINEE ONLY IN THE LIMITED CIRCUMSTANCES DESCRIBED IN THE PURCHASE CONTRACT
AGREEMENT AND NO TRANSFER OF THIS CERTIFICATE (OTHER THAN A TRANSFER OF THIS
CERTIFICATE AS A WHOLE BY THE DEPOSITARY TO A NOMINEE OF THE DEPOSITARY OR BY A
NOMINEE OF THE DEPOSITARY TO THE DEPOSITARY OR ANOTHER NOMINEE OF THE
DEPOSITARY) MAY BE REGISTERED EXCEPT IN LIMITED CIRCUMSTANCES.

         UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF
THE DEPOSITARY FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND ANY
CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR SUCH OTHER NAME AS
REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITARY (AND ANY PAYMENT
HEREON IS MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN
AUTHORIZED REPRESENTATIVE OF THE DEPOSITARY), ANY TRANSFER, PLEDGE OR OTHER USE
HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL SINCE THE
REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN."

No. 1                                                        Cusip No. 91821d107
Number of PEPS Units 6,900,000

                            VALERO ENERGY CORPORATION
                                   VEC TRUST I
                                   PEPS UNITS

         This PEPS Units Certificate certifies that Cede & Co. is the registered
Holder of the number of PEPS Units set forth above. Each PEPS Unit consists of
(i) either (a) the beneficial ownership by the Holder of one Preferred Security
(the "PREFERRED SECURITY") of VEC Trust I, a Delaware statutory business trust
(the "TRUST"), having a stated liquidation amount of $25, subject to the Pledge
of such Preferred Security by such Holder pursuant to the Pledge Agreement, or
(b) upon the occurrence of a Tax Event Redemption prior to the Purchase Contract
Settlement Date, the appropriate Applicable Ownership Interest (as specified in
clause

<PAGE>   73

(A) of the definition of such term) of the Treasury Portfolio by such Holder
pursuant to the Pledge Agreement, and (ii) the rights and obligations of the
Holder under one Purchase Contract with Valero Energy Corporation, a Delaware
corporation (the "COMPANY"). All capitalized terms used herein which are defined
in the Purchase Contract Agreement (as defined on the reverse hereof) have the
meaning set forth therein.

         Pursuant to the Pledge Agreement, the Preferred Securities or the
appropriate Applicable Ownership Interest (as specified in clause (A) of the
definition of such term) of the Treasury Portfolio, as the case may be,
constituting part of each PEPS Unit evidenced hereby has been pledged to the
Collateral Agent, for the benefit of the Company, to secure the obligations of
the Holder under the Purchase Contract comprising part of such PEPS Unit.

         The Pledge Agreement provides that all payments of the liquidation
amount with respect to any of the Pledged Preferred Securities or the
appropriate Applicable Ownership Interest (as specified in clause (A) of the
definition of such term) of the Treasury Portfolio, as the case may be, or cash
distributions on any Pledged Preferred Securities (as defined in the Pledge
Agreement) or the appropriate Applicable Ownership Interest (as specified in
clause (B) of the definition of such term) of the Treasury Portfolio, as the
case may be, constituting part of the PEPS Units received by the Securities
Intermediary shall be paid by wire transfer in same day funds (i) in the case of
(A) cash distributions with respect to Pledged Preferred Securities or the
appropriate Applicable Ownership Interest (as specified in clause (B) of the
definition of such term) of the Treasury Portfolio, as the case may be, and (B)
any payments of the liquidation amount with respect to any Preferred Securities
or the appropriate Applicable Ownership Interest (as specified in clause (A) of
the definition of such term) of the Treasury Portfolio, as the case may be, that
have been released from the Pledge pursuant to the Pledge Agreement, to the
Purchase Contract Agent to the account designated by the Purchase Contract
Agent, no later than 2:00 p.m., New York City time, on the Business Day such
payment is received by the Securities Intermediary (provided that in the event
such payment is received by the Securities Intermediary on a day that is not a
Business Day or after 12:30 p.m., New York City time, on a Business Day, then
such payment shall be made no later than 10:30 a.m., New York City time, on the
next succeeding Business Day) and (ii) in the case of payments of the
liquidation amount with respect to any of the Pledged Preferred Securities or
the appropriate Applicable Ownership Interest (as specified in clause (A) of the
definition of such term) of the Treasury Portfolio, to the Company on the
Purchase Contract Settlement Date (as described herein) in accordance with the
terms of the Pledge Agreement, in full satisfaction of the respective
obligations of the Holders of the PEPS Units of which such Pledged Preferred
Securities or the Applicable Ownership Interest (as specified in clause (A) of
the definition of such term) of the Treasury Portfolio, as the case may be, are
a part under the Purchase Contracts forming a part of such PEPS Units.
Distributions on any Preferred Security or the appropriate Applicable Ownership
Interest (as specified in clause (B) of the definition of such term) of the
Treasury Portfolio, as the case may be, forming part of a PEPS Unit evidenced
hereby, which are payable quarterly in arrears on February 18, May 18, August
18, and November 18 of each year, commencing August 18, 2000 (a "PAYMENT DATE"),
shall, subject to receipt thereof by the Purchase Contract Agent from the
Securities Intermediary,

                                       A-2
<PAGE>   74

be paid to the Person in whose name this PEPS Unit Certificate (or a Predecessor
PEPS Unit Certificate) is registered at the close of business on the Record Date
for such Payment Date.

         Each Purchase Contract evidenced hereby obligates the Holder of this
PEPS Units Certificate to purchase, and the Company to sell, on August 18, 2003
(the "PURCHASE CONTRACT SETTLEMENT DATE"), at a price equal to $25 (the "STATED
AMOUNT"), a number of shares of Common Stock, $0.01 par value ("COMMON STOCK"),
of the Company, equal to the Settlement Rate, unless on or prior to the Purchase
Contract Settlement Date there shall have such occurred a Termination Event or
an Early Settlement with respect to the PEPS Unit of which such Purchase
Contract is a part, all as provided in the Purchase Contract Agreement and more
fully described on the reverse hereof. The purchase price (the "PURCHASE PRICE")
for the shares of Common Stock purchased pursuant to each Purchase Contract
evidenced hereby, if not paid earlier, shall be paid on the Purchase Contract
Settlement Date by application of payment received in respect of the liquidation
amount with respect to any Pledged Preferred Securities pursuant to the
Remarketing or the appropriate Applicable Ownership Interest (as specified in
clause (A) of the definition of such term) of the Treasury Portfolio, as the
case may be, pledged to secure the obligations under such Purchase Contract of
the Holder of the PEPS Unit of which such Purchase Contract is a part.

         Distributions on the Preferred Securities and the Applicable Ownership
Interest (as specified in clause (B) of the definition of such term) will be
payable at the office of the Purchase Contract Agent in New York City or, at the
option of the Company, by check mailed to the address of the Person entitled
thereto as such address appears on the PEPS Units Register.

         Reference is hereby made to the further provisions set forth on the
reverse hereof, which further provisions shall for all purposes have the same
effect as if set forth at this place.

         Unless the certificate of authentication hereon has been executed by
the Purchase Contract Agent by manual signature, this PEPS Units Certificate
shall not be entitled to any benefit under the Pledge Agreement or the Purchase
Contract Agreement or be valid or obligatory for any purpose.

                                       A-3
<PAGE>   75

         IN WITNESS WHEREOF, the Company has caused this instrument to be duly
executed.

                                       VALERO ENERGY CORPORATION

                                     By:
                                        ----------------------------------------
                                        Name: John D. Gibbons
                                        Title: Vice President and Chief
                                               Financial Officer

                                     HOLDER SPECIFIED ABOVE (as to
                                     obligations of such Holder under the
                                     Purchase Contracts)

                                     By: THE BANK OF NEW YORK, not
                                     individually but solely as Attorney-in-Fact
                                     of such Holder

                                     By:
                                        ----------------------------------------
                                        Name:
                                        Title:

DATED: June 28, 2000

                                       A-4
<PAGE>   76

                          CERTIFICATE OF AUTHENTICATION
                           OF PURCHASE CONTRACT AGENT

         This is one of the PEPS Units Certificates referred to in the within
mentioned Purchase Contract Agreement.

                                       By: THE BANK OF NEW YORK, as
                                       Purchase Contract Agent

                                       By:
                                          --------------------------------------
                                                  Authorized Signatory

Dated: June 28, 2000

                                       A-5
<PAGE>   77

                   (FORM OF REVERSE OF PEPS UNITS CERTIFICATE)

         Each Purchase Contract evidenced hereby is governed by a Purchase
Contract Agreement, dated as of June 28, 2000 (as may be supplemented from time
to time, the "PURCHASE CONTRACT AGREEMENT"), between the Company and The Bank of
New York, as Purchase Contract Agent (including its successors hereunder, the
"PURCHASE CONTRACT AGENT"), to which Purchase Contract Agreement and
supplemental agreements thereto reference is hereby made for a description of
the respective rights, limitations of rights, obligations, duties and immunities
thereunder of the Purchase Contract Agent, the Company, and the Holders and of
the terms upon which the PEPS Units Certificates are, and are to be, executed
and delivered.

         Unless a Cash Settlement or an Early Settlement has occurred, each
Purchase Contract evidenced hereby obligates the Holder of this PEPS Units
Certificate to purchase, and the Company to sell, on the Purchase Contract
Settlement Date at a price equal to the Stated Amount (the "PURCHASE PRICE"), a
number of shares of Common Stock equal to the Settlement Rate, unless, prior to
or on the Purchase Contract Settlement Date, there shall have occurred a
Termination Event with respect to the Security of which such Purchase Contract
is a part or an Early Settlement shall have occurred. The "SETTLEMENT RATE" is
equal to:

                  (1) if the Applicable Market Value (as defined below) is
         greater than or equal to $34.95 (the "THRESHOLD APPRECIATION PRICE"),
         .71531 shares of Common Stock per Purchase Contract;

                  (2) if the Applicable Market Value is less than the Threshold
         Appreciation Price but greater than $29.125 (the "REFERENCE PRICE"),
         the number of shares of Common Stock per Purchase Contract having a
         value, based on the Applicable Market Value, equal to $25; and

                  (3) if the Applicable Market Value is less than or equal to
         the Reference Price, .85837 shares of Common Stock per Purchase
         Contract,

in each case subject to adjustment as provided in the Purchase Contract
Agreement (and in each case rounded upward or downward to the nearest 1/10,000th
of a share).

         No fractional shares of Common Stock will be issued upon settlement of
Purchase Contracts, as provided in Section 5.09 of the Purchase Contract
Agreement.

         Each Purchase Contract evidenced hereby, which is settled either
through Early Settlement or Cash Settlement, shall obligate the Holder of the
related PEPS Unit to purchase at the Purchase Price, and the Company to sell, a
number of shares of Common Stock equal to the Early Settlement Rate or the
Settlement Rate, as applicable.

                                       A-6
<PAGE>   78

         The "APPLICABLE MARKET VALUE" means the average of the Closing Price
per share of Common Stock on each of the 20 consecutive Trading Days ending on
the third Trading Day immediately preceding the Purchase Contract Settlement
Date.

         The "CLOSING PRICE" per share of Common Stock on any date of
determination means:

                  (1) the closing sale price (or, if no closing price is
         reported, the last reported sale price) per share on the New York Stock
         Exchange, Inc. (the "NYSE") on such date;

                  (2) if Common Stock is not listed for trading on the NYSE on
         any such date, the closing sale price per share as reported in the
         composite transactions for the principal United States securities
         exchange on which Common Stock is so listed;

                  (3) if Common Stock is not so listed on a United States
         national or regional securities exchange, the closing sale price per
         share as reported by The NASDAQ Stock Market, Inc.;

                  (4) if Common Stock is not so reported, the last quoted bid
         price for Common Stock in the over-the-counter market as reported by
         the National Quotation Bureau or similar organization; or

                  (5) if such bid price is not available, the average of the
         mid-point of the last bid and ask prices of Common Stock on such date
         from at least three nationally recognized independent investment
         banking firms retained for this purpose by the Company.

         A "TRADING DAY" means a day on which Common Stock (1) is not suspended
from trading on any national or regional securities exchange or association or
over-the-counter market at the close of business and (2) has traded at least
once on the national or regional securities exchange or association or
over-the-counter market that is the primary market for the trading of Common
Stock.

         In accordance with the terms of the Purchase Contract Agreement, the
Holder of this PEPS Units Certificate may pay the Purchase Price for the shares
of Common Stock purchased pursuant to each Purchase Contract evidenced hereby by
effecting a Cash Settlement or an Early Settlement or from the proceeds of the
Applicable Ownership Interest (as specified in clause (A) of the definition of
such term) of the Treasury Portfolio or a Remarketing of the related Pledged
Preferred Securities. A Holder of PEPS Units who does not effect, on or prior to
11:00 a.m. (New York City time) on the fifth Business Day immediately preceding
the Purchase Contract Settlement Date (or in the event a Tax Event Redemption
has occurred, the Business Day prior to the Purchase Contract Settlement Date),
an effective Cash Settlement or, who does not effect on or prior to 5:00 p.m.
(New York City time) on the seventh Business Day prior to the Purchase Contract
Settlement Date, an effective Early Settlement, shall pay the Purchase Price for
the shares of Common Stock to be delivered under the related Purchase Contract
from the proceeds

                                       A-7
<PAGE>   79

of the sale of the related Pledged Preferred Securities held by the Collateral
Agent. Such sale will be made by the Remarketing Agent pursuant to the terms of
the Remarketing Agreement on the third Business Day prior to the Purchase
Contract Settlement Date. If, as provided in the Purchase Contract Agreement,
upon the occurrence of a Failed Remarketing, the Collateral Agent, for the
benefit of the Company, exercises its rights as a secured creditor with respect
to the Pledged Preferred Securities related to this PEPS Units certificate, any
accrued and unpaid distributions on such Pledged Preferred Securities will
become payable by the Company to the holder of this PEPS Units Certificate in
the manner provided for in the Purchase Contract Agreement.

         The Company shall not be obligated to issue any shares of Common Stock
in respect of a Purchase Contract or deliver any certificates therefor to the
Holder unless it shall have received payment of the aggregate purchase price for
the shares of Common Stock to be purchased thereunder in the manner herein set
forth.

         Each Purchase Contract evidenced hereby and all obligations and rights
of the Company and the Holder thereunder shall terminate if a Termination Event
shall occur. Upon the occurrence of a Termination Event, the Company shall give
written notice to the Purchase Contract Agent and to the Holders, at their
addresses as they appear in the PEPS Unit Register. Upon and after the
occurrence of a Termination Event, the Collateral Agent shall release the
Pledged Preferred Security or the appropriate Applicable Ownership Interest (as
specified in clause (A) of the definition of such term) of the Treasury
Portfolio forming a part of each PEPS Unit from the Pledge. A PEPS Unit shall
thereafter represent the right to receive the Preferred Security or the
appropriate Applicable Ownership Interest of the Treasury Portfolio forming a
part of such PEPS Unit in accordance with the terms of the Purchase Contract
Agreement and the Pledge Agreement.

         Under the terms of the Pledge Agreement, the Purchase Contract Agent
will be entitled to exercise the voting and any other consensual rights
pertaining to the Pledged Preferred Securities. Upon receipt of notice of any
meeting at which holders of Preferred Securities are entitled to vote or upon
the solicitation of consents, waivers or proxies of holders of Preferred
Securities, the Purchase Contract Agent shall, as soon as practicable
thereafter, mail to the PEPS Units Holders a notice:

                  (1) containing such information as is contained in the notice
         or solicitation;

                  (2) stating that each PEPS Unit Holder on the record date set
         by the Purchase Contract Agent therefor (which, to the extent possible,
         shall be the same date as the record date for determining the holders
         of Preferred Securities entitled to vote) shall be entitled to instruct
         the Purchase Contract Agent as to the exercise of the voting rights
         pertaining to the Preferred Securities constituting a part of such
         Holder's PEPS Unit; and

                  (3) stating the manner in which such instructions may be
         given.

                                       A-8
<PAGE>   80

Upon the written request of the PEPS Unit Holders on such record date, the
Purchase Contract Agent shall endeavor insofar as practicable to vote or cause
to be voted, in accordance with the instructions set forth in such requests, the
maximum number of Preferred Securities as to which any particular voting
instructions are received. In the absence of specific instructions from the
Holder of a PEPS Unit, the Purchase Contract Agent shall abstain from voting the
Preferred Security evidenced by such PEPS Unit.

         Upon the dissolution and liquidation of the Trust, a principal amount
of the Senior Deferrable Notes constituting the assets of the Trust and
underlying the Preferred Securities equal to the aggregate liquidation amount of
the Pledged Preferred Securities shall be delivered to the Securities
Intermediary in exchange for the Pledged Preferred Securities. Thereafter, the
Senior Deferrable Notes shall be held by the Securities Intermediary to secure
the obligations of each Holder of PEPS Units to purchase shares of Common Stock
under the Purchase Contracts constituting a part of such PEPS Units. Following
the dissolution and liquidation of the Trust, the Holders and the Collateral
Agent shall have such security interests, rights and obligations with respect to
the Senior Deferrable Notes as the Holders and the Collateral Agent had in
respect of the Pledged Preferred Securities, any reference herein to the
Preferred Securities shall be deemed to be a reference to the Senior Deferrable
Notes and any reference herein to the liquidation amount of the Preferred
Securities shall be deemed to be a reference to the principal amount of the
Senior Deferrable Notes.

         Upon the occurrence of a Tax Event Redemption prior to the Purchase
Contract Settlement Date, the Redemption Price payable on the Tax Event
Redemption Date with respect to the Applicable Principal Amount of Senior
Deferrable Notes shall be delivered to the Securities Intermediary in exchange
for the Pledged Preferred Securities. Thereafter, pursuant to the terms of the
Pledge Agreement, the Securities Intermediary will apply an amount equal to the
Redemption Amount of such Redemption Price to purchase on behalf of the Holders
of PEPS Units, the Treasury Portfolio and promptly (a) transfer the Applicable
Ownership Interest (as specified in clause (A) of the definition of such term)
of the Treasury Portfolio to the Collateral Account to secure the obligations of
each Holder of PEPS Units to purchase shares of Common Stock under the Purchase
Contracts constituting a part of such PEPS Units, (b) transfer the Applicable
Ownership Interest (as specified in clause (B) of the definition of such term)
of the Treasury Portfolio to the Purchase Contract Agent for the benefit of the
Holders of such PEPS Units and (C) remit the remaining portion of such
Redemption Price to the Purchase Contract Agent for payment to the Holders of
such PEPS Units.

         Following the occurrence of a Tax Event Redemption prior to the
Purchase Contract Settlement Date, the Holders of PEPS Units and the Collateral
Agent shall have such security interest rights and obligations with respect to
the Applicable Ownership Interest (as specified in clause (A) of the definition
of such term) of the Treasury Portfolio as the Holder of PEPS Units and the
Collateral Agent had in respect of the Preferred Securities or Senior Deferrable
Notes, as the case may be, subject to the Pledge thereof as provided in the
Pledge Agreement and any

                                       A-9
<PAGE>   81

reference herein to the Preferred Securities shall be deemed to be a reference
to such Treasury Portfolio.

         The PEPS Certificates are issuable only in registered form and only in
denominations of a single PEPS Unit and any integral multiple thereof. The
transfer of any PEPS Units Certificate will be registered and PEPS Units
Certificates may be exchanged as provided in the Purchase Contract Agreement.
The PEPS Units Registrar may require a Holder, among other things, to furnish
appropriate endorsements and transfer documents permitted by the Purchase
Contract Agreement. No service charge shall be required for any such
registration of transfer or exchange, but the Company and the Purchase Contract
Agent may require payment of a sum sufficient to cover any tax or other
governmental charge payable in connection therewith. A Holder who elects to
substitute a Treasury Security for Preferred Securities, thereby creating
Treasury PEPS Units, shall be responsible for any fees or expenses payable in
connection therewith. Except as provided in the Purchase Contract Agreement, for
so long as the Purchase Contract underlying a PEPS Unit remains in effect, such
PEPS Unit shall not be separable into its constituent parts, and the rights and
obligations of the Holder of such PEPS Unit in respect of the Preferred
Securities and Purchase Contract constituting such PEPS Unit may be transferred
and exchanged only as a PEPS Unit.

         The Holder of PEPS Units may substitute for the Pledged Preferred
Securities securing such Holder's obligations under the related Purchase
Contracts Treasury Securities in an aggregate principal amount equal to the
aggregate liquidation amount of the Pledged Preferred Securities in accordance
with the terms of the Purchase Contract Agreement and the Pledge Agreement. From
and after such Collateral Substitution, each Security for which such Pledged
Treasury Securities secures the Holder's obligation under the Purchase Contract
shall be referred to as a "TREASURY PEPS UNIT". A Holder may make such
Collateral Substitution only in integral multiples of 40 PEPS Units for 40
Treasury PEPS Units.

         A Holder of Treasury PEPS Units may recreate PEPS Units by delivering
to the Securities Intermediary Preferred Securities equal to the aggregate
principal amount of the Pledged Treasury Securities in exchange for the release
of such Pledged Treasury Securities in accordance with the terms of the Purchase
Contract Agreement and the Pledge Agreement. A Holder may recreate PEPS Units in
integral multiples of 40 Treasury PEPS Units for 40 PEPS Units.

         If a Tax Event Redemption has occurred, a PEPS Unit Holder may not
create Treasury Peps Units, and a Treasury PEPS Unit Holder may not recreate a
PEPS Unit.

         The Purchase Contracts and all obligations and rights of the Company
and the Holders thereunder shall immediately and automatically terminate,
without the necessity of any notice or action by any Holder, the Purchase
Contract Agent or the Company, if, on or prior to the Purchase Contract
Settlement Date, a Termination Event shall have occurred. Upon the occurrence of
a Termination Event, the Company shall promptly but in no event later than two

                                      A-10
<PAGE>   82

Business Days thereafter give written notice to the Purchase Contract Agent, the
Collateral Agent and the Holders, at their addresses as they appear in the PEPS
Units Register. Upon and after the occurrence of a Termination Event, the
Collateral Agent shall release the Preferred Securities or the appropriate
Applicable Ownership Interest (as specified in clause (A) of the definition of
such term) of the Treasury Portfolio, as the case may be, from the Pledge in
accordance with the provisions of the Pledge Agreement.

         Subject to and upon compliance with the provisions of the Purchase
Contract Agreement, at the option of the Holder thereof, Purchase Contracts
underlying Securities may be settled early ("EARLY SETTLEMENT") as provided in
the Purchase Contract Agreement. In order to exercise the right to effect Early
Settlement with respect to any Purchase Contracts evidenced by this PEPS Units
Certificate, the Holder of this PEPS Units Certificate shall deliver to the
Purchase Contract Agent at the Corporate Trust Office an Election to Settle
Early form set forth below and any other documents requested by the Purchase
Contract Agent duly completed and accompanied by payment in the form of
immediately available funds payable to the order of the Company in an amount
(the "EARLY SETTLEMENT AMOUNT") equal to the product of (A) $25 times (B) the
number of Purchase Contracts with respect to which the Holder has elected to
effect Early Settlement.

Upon Early Settlement of Purchase Contracts by a Holder of the related
Securities, the Pledged Preferred Securities or the appropriate Applicable
Ownership Interest (as specified in clause (A) of the definition of such term)
of the Treasury Portfolio, as the case may be, underlying such Securities shall
be released from the Pledge as provided in the Pledge Agreement and the Holder
shall be entitled to receive a number of shares of Common Stock on account of
each Purchase Contract forming part of a PEPS Unit as to which Early Settlement
is effected equal to .71531 shares of Common Stock per Purchase Contract (the
"EARLY SETTLEMENT RATE"). The Early Settlement Rate shall be adjusted in the
same manner and at the same time as the Settlement Rate is adjusted as provided
in the Purchase Contract Agreement.

         Upon registration of transfer of this PEPS Units Certificate, the
transferee shall be bound (without the necessity of any other action on the part
of such transferee, except as may be required by the Purchase Contract Agent
pursuant to the Purchase Contract Agreement), under the terms of the Purchase
Contract Agreement and the Purchase Contracts evidenced hereby and the
transferor shall be released from the obligations under the Purchase Contracts
evidenced by this PEPS Units Certificate. The Company covenants and agrees, and
the Holder, by its acceptance hereof, likewise covenants and agrees, to be bound
by the provisions of this paragraph.

         The Holder of this PEPS Units Certificate, by its acceptance hereof,
authorizes the Purchase Contract Agent to enter into and perform the related
Purchase Contracts forming part of the PEPS Units evidenced hereby on its behalf
as its attorney-in-fact, expressly withholds any consent to the assumption
(i.e., affirmance) of the Purchase Contracts by the Company or its trustee in
the event that the Company becomes the subject of a case under the Bankruptcy
Code, agrees to be bound by the terms and provisions thereof, covenants and
agrees to perform his

                                      A-11
<PAGE>   83

obligations under such Purchase Contracts, consents to the provisions of the
Purchase Contract Agreement, authorizes the Purchase Contract Agent to enter
into and perform the Purchase Contract Agreement and the Pledge Agreement on its
behalf as its attorney-in-fact, and consents to the Pledge of the Preferred
Securities or the appropriate Applicable Ownership Interest (as specified in
clause (A) of the definition of such term) of the Treasury Portfolio, as the
case may be, underlying this PEPS Units Certificate pursuant to the Pledge
Agreement. The Holder further covenants and agrees that, to the extent and in
the manner provided in the Purchase Contract Agreement and the Pledge Agreement,
but subject to the terms thereof, payments in respect to the aggregate
liquidation amount of the Pledged Preferred Securities or the appropriate
Applicable Ownership Interest (as specified in clause (A) of the definition of
such term) of the Treasury Portfolio, as the case may be, on the Purchase
Contract Settlement Date shall be paid by the Collateral Agent to the Company in
satisfaction of such Holder's obligations under such Purchase Contract and such
Holder shall acquire no right, title or interest in such payments.

         Subject to certain exceptions, the provisions of the Purchase Contract
Agreement may be amended with the consent of the Holders of a majority of the
Purchase Contracts.

         The Purchase Contracts shall be governed by, and construed in
accordance with, the laws of the State of New York.

         The Company, the Purchase Contract Agent and its Affiliates and any
agent of the Company or the Purchase Contract Agent may treat the Person in
whose name this PEPS Units Certificate is registered as the owner of the PEPS
Units evidenced hereby for the purpose of receiving payments of distributions
payable quarterly on the Preferred Securities, performance of the Purchase
Contracts and for all other purposes whatsoever, whether or not any payments in
respect thereof be overdue and notwithstanding any notice to the contrary, and
neither the Company, the Purchase Contract Agent nor any such agent shall be
affected by notice to the contrary.

         The Purchase Contracts shall not, prior to the settlement thereof,
entitle the Holder to any of the rights of a holder of shares of Common Stock.

         A copy of the Purchase Contract Agreement is available for inspection
at the offices of the Purchase Contract Agent.

                                      A-12
<PAGE>   84

                                  ABBREVIATIONS

         The following abbreviations, when used in the inscription on the face
of this instrument, shall be construed as though they were written out in full
according to applicable laws or regulations:

TEN COM:                     as tenants in common
UNIF GIFT MIN ACT:                               Custodian
                             -------------------           -------------------
                                   (cust)                        (minor)
                             Under Uniform Gifts to Minors Act of
                                                                   -----------

                             --------------------------------------------------

TENANT:                      as tenants by the entireties

JT TEN:                      as joint tenants with right of survivorship and not
                             as tenants in common

Additional abbreviations may also be used though not in the above list.

                                   ----------

         FOR VALUE RECEIVED, the undersigned hereby sell(s), assign(s) and
transfer(s) unto

--------------------------------------------------------------------------------
      (Please insert Social Security or Taxpayer I.D. or other Identifying
                              Number of Assignee)

--------------------------------------------------------------------------------
  (Please Print or Type Name and Address Including Postal Zip Code of Assignee)

the within PEPS Units Certificates and all rights thereunder, hereby irrevocably
constituting and appointing attorney __________________, to transfer said PEPS
Units Certificates on the books of Valero Energy Corporation and VEC Trust I
with full power of substitution in the premises.

Dated:                                 Signature
      ----------------------------              --------------------------------

                                       NOTICE: The signature to this assignment
                                       must correspond with the name as it
                                       appears upon the face of the within PEPS
                                       Units Certificates in every particular,
                                       without alteration or enlargement or any
                                       change whatsoever.

         Signature Guarantee:
                             --------------------------------

                                      A-13
<PAGE>   85

                             SETTLEMENT INSTRUCTIONS

         The undersigned Holder directs that a certificate for shares of Common
Stock deliverable upon settlement on or after the Purchase Contract Settlement
Date of the Purchase Contracts underlying the number of PEPS Units evidenced by
this PEPS Units Certificate be registered in the name of, and delivered,
together with a check in payment for any fractional share, to the undersigned at
the address indicated below unless a different name and address have been
indicated below. If shares are to be registered in the name of a Person other
than the undersigned, the undersigned will pay any transfer tax payable incident
thereto.

Dated:
      ---------------------------------     ------------------------------------
                                            Signature
                                            Signature Guarantee:
                                                                ----------------
                                            (if assigned to another person)

If shares are to be registered in the
name of and delivered to a Person other     REGISTERED HOLDER
than the Holder, please (i) print such
Person's name and address and (ii)          Please print name and address of
provide a guarantee of your signature:      Registered Holder:

---------------------------------------     ------------------------------------
Name                                        Name

---------------------------------------     ------------------------------------
Address                                     Address

---------------------------------------     ------------------------------------
---------------------------------------     ------------------------------------
---------------------------------------     ------------------------------------

Social Security or other
Taxpayer Identification
Number, if any
                                            ------------------------------------

                                      A-14
<PAGE>   86

                            ELECTION TO SETTLE EARLY

         The undersigned Holder of this PEPS Units Certificate hereby
irrevocably exercises the option to effect Early Settlement in accordance with
the terms of the Purchase Contract Agreement with respect to the Purchase
Contracts underlying the number of PEPS Units evidenced by this PEPS Units
Certificate specified below. The undersigned Holder directs that a certificate
for shares of Common Stock deliverable upon such Early Settlement be registered
in the name of, and delivered, together with a check in payment for any
fractional share and any PEPS Units Certificate representing any PEPS Units
evidenced hereby as to which Early Settlement of the related Purchase Contracts
is not effected, to the undersigned at the address indicated below unless a
different name and address have been indicated below. Pledged Preferred
Securities or the appropriate Applicable Ownership Interest of the Treasury
Portfolio, as the case may be, deliverable upon such Early Settlement will be
transferred in accordance with the transfer instructions set forth below. If
shares are to be registered in the name of a Person other than the undersigned,
the undersigned will pay any transfer tax payable incident thereto.

Dated:
      -----------------------               ------------------------------------
                                            Signature

Signature Guarantee:
                    -----------------------

                                      A-15
<PAGE>   87

         Number of Securities evidenced hereby as to which Early Settlement of
the related Purchase Contracts is being elected:

If shares of Common Stock or PEPS           REGISTERED HOLDER
Units Certificates are to be
registered in the name of and
delivered to and Pledged Preferred
Securities, or the Applicable
Ownership Interest of the Treasury
Portfolio, as the case may be, are to
be transferred to a Person other than
the Holder, please print such Person's
name and address:

                                            Please print name and address of
                                            Registered Holder:

---------------------------------------     ------------------------------------
Name                                        Name

--------------------------------------      ------------------------------------
Address                                     Address

--------------------------------------      ------------------------------------
--------------------------------------      ------------------------------------
--------------------------------------      ------------------------------------

Social Security or other
Taxpayer Identification

Number, if any
                                            ------------------------------------

                                      A-16
<PAGE>   88

Transfer Instructions for Pledged Preferred Securities or the Applicable
Ownership Interest of the Treasury Portfolio, as the case may be, transferable
upon Early Settlement or a Termination Event:

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------

                                      A-17
<PAGE>   89

                     [TO BE ATTACHED TO GLOBAL CERTIFICATES]

            SCHEDULE OF INCREASES OR DECREASES IN GLOBAL CERTIFICATE

The following increases or decreases in this Global Certificate have been made:

<TABLE>
<CAPTION>
=======================================================================================================================
                                                                         Number of PEPS Units
                         Amount of increase in   Amount of decrease in     evidenced by this
                         Number of PEPS Units    Number of PEPS Units     Global Certificate    Signature of authorized
                           evidenced by the        evidenced by the         following such      officer of Trustee or
Date                      Global Certificate      Global Certificate     decrease or increase   Securities Custodian
<S>                     <C>                      <C>                     <C>                    <C>

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------
</TABLE>

                                      A-18
<PAGE>   90

                                                                       EXHIBIT B

                        FACE OF TREASURY PEPS CERTIFICATE

         "THIS CERTIFICATE IS A GLOBAL CERTIFICATE WITHIN THE MEANING OF THE
PURCHASE CONTRACT AGREEMENT HEREINAFTER REFERRED TO AND IS REGISTERED IN THE
NAME OF THE DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION (THE "DEPOSITARY"),
OR A NOMINEE OF THE DEPOSITARY. THIS CERTIFICATE IS EXCHANGEABLE FOR
CERTIFICATES REGISTERED IN THE NAME OF A PERSON OTHER THAN THE DEPOSITARY OR ITS
NOMINEE ONLY IN THE LIMITED CIRCUMSTANCES DESCRIBED IN THE PURCHASE CONTRACT
AGREEMENT AND NO TRANSFER OF THIS CERTIFICATE (OTHER THAN A TRANSFER OF THIS
CERTIFICATE AS A WHOLE BY THE DEPOSITARY TO A NOMINEE OF THE DEPOSITARY OR BY A
NOMINEE OF THE DEPOSITARY TO THE DEPOSITARY OR ANOTHER NOMINEE OF THE
DEPOSITARY) MAY BE REGISTERED EXCEPT IN LIMITED CIRCUMSTANCES.

         UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF
THE DEPOSITARY FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND ANY
CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR SUCH OTHER NAME AS
REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITARY (AND ANY PAYMENT
HEREON IS MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN
AUTHORIZED REPRESENTATIVE OF THE DEPOSITARY), ANY TRANSFER, PLEDGE OR OTHER USE
HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL SINCE THE
REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN."

No.  1                                                       Cusip No. 91913y209
Number of Treasury PEPS Units 0

                            VALERO ENERGY CORPORATION
                                   VEC TRUST I
                               TREASURY PEPS UNITS

         This Treasury PEPS Units Certificate certifies that Cede & Co. is the
registered Holder of the number of Treasury PEPS Units set forth above. Each
Treasury PEPS Unit consists of (i) a 1/40 undivided beneficial ownership
interest of a Treasury Security having a principal amount at maturity equal to
$1,000, subject to the Pledge of such Treasury Security by such Holder pursuant
to the Pledge Agreement, and (ii) the rights and obligations of the Holder under
one Purchase Contract with Valero Energy Corporation, a Delaware corporation
(the "COMPANY"). All capitalized terms used herein which are defined in the
Purchase Contract Agreement (as defined on the reverse hereof) have the meaning
set forth therein.

<PAGE>   91

         Pursuant to the Pledge Agreement, the Treasury Securities constituting
part of each Treasury PEPS Unit evidenced hereby have been pledged to the
Collateral Agent, for the benefit of the Company, to secure the obligations of
the Holder under the Purchase Contract comprising part of such Treasury PEPS
Unit. Each Purchase Contract evidenced hereby obligates the Holder of this
Treasury PEPS Units Certificate to purchase, and the Company, to sell, on August
18, 2003, at a price equal to $25 (the "STATED AMOUNT"), a number of shares of
Common Stock, $0.01 par value ("COMMON STOCK"), of the Company, equal to the
Settlement Rate, unless prior to or on the Purchase Contract Settlement Date
there shall have occurred a Termination Event or an Early Settlement with
respect to the Treasury PEPS Unit of which such Purchase Contract is a part, all
as provided in the Purchase Contract Agreement and more fully described on the
reverse hereof. The purchase price (the "PURCHASE PRICE") for the shares of
Common Stock purchased pursuant to each Purchase Contract evidenced hereby, if
not paid earlier, shall be paid on the Purchase Contract Settlement Date by
application of the proceeds from the Treasury Securities at maturity pledged to
secure the obligations of the Holder under such Purchase Contract of the
Treasury PEPS Unit of which such Purchase Contract is a part.

         Reference is hereby made to the further provisions set forth on the
reverse hereof, which further provisions shall for all purposes have the same
effect as if set forth at this place.

         Unless the certificate of authentication hereon has been executed by
the Purchase Contract Agent by manual signature, this Treasury PEPS Units
Certificate shall not be entitled to any benefit under the Pledge Agreement or
the Purchase Contract Agreement or be valid or obligatory for any purpose.

                                       B-2
<PAGE>   92

         IN WITNESS WHEREOF, the Company has caused this instrument to be duly
executed.

                                       VALERO ENERGY CORPORATION

                                       By:
                                          --------------------------------------
                                          Name: John D. Gibbons
                                          Title: Vice President and Chief
                                                 Financial Officer

                                       HOLDER SPECIFIED ABOVE (as to
                                       obligations of such Holder under the
                                       Purchase Contracts)

                                       By: THE BANK OF NEW YORK, not
                                           individually but solely as Attorney-
                                           in-Fact of such Holder

                                       By:
                                          --------------------------------------
                                          Name:
                                          Title:

Dated: June 28, 2000

                                       B-3
<PAGE>   93

                        CERTIFICATE OF AUTHENTICATION OF
                             PURCHASE CONTRACT AGENT

         This is one of the Treasury PEPS Units referred to in the
within-mentioned Purchase Contract Agreement.

                                       By: THE BANK OF NEW YORK, as
                                           Purchase Contract Agent

                                       By:
                                          --------------------------------------
                                                  Authorized Signatory

Dated: June 28, 2000

                                       B-4
<PAGE>   94

                  (REVERSE OF TREASURY PEPS UNITS CERTIFICATE)

         Each Purchase Contract evidenced hereby is governed by a Purchase
Contract Agreement, dated as of June 28, 2000 (as may be supplemented from time
to time, the "PURCHASE CONTRACT AGREEMENT") between the Company and The Bank of
New York, as Purchase Contract Agent (including its successors thereunder,
herein called the "PURCHASE CONTRACT AGENT"), to which the Purchase Contract
Agreement and supplemental agreements thereto reference is hereby made for a
description of the respective rights, limitations of rights, obligations, duties
and immunities thereunder of the Purchase Contract Agent, the Company and the
Holders and of the terms upon which the Treasury PEPS Units Certificates are,
and are to be, executed and delivered.

         Unless a Cash Settlement or an Early Settlement has occurred, each
Purchase Contract evidenced hereby obligates the Holder of this Treasury PEPS
Units Certificate to purchase, and the Company to sell, on the Purchase Contract
Settlement Date at a price equal to the Stated Amount (the "PURCHASE PRICE") a
number of shares of Common Stock equal to the Settlement Rate, unless prior to
the Purchase Contract Settlement Date, there shall have occurred a Termination
Event with respect to the Security of which such Purchase Contract is a part or
an Early Settlement shall have occurred. The "SETTLEMENT RATE" is equal to:

                  (1) if the Applicable Market Value (as defined below) is
         greater than or equal to $34.95 (the "THRESHOLD APPRECIATION PRICE"),
         .71531 shares of Common Stock per Purchase Contract;

                  (2) if the Applicable Market Value is less than the Threshold
         Appreciation Price but greater than $29.125 (the "REFERENCE PRICE"),
         the number of shares of Common Stock per Purchase Contract having a
         value, based on the Applicable Market Value, equal to $25; and

                  (3) if the Applicable Market Value is less than or equal to
         $29.125, then .85837 shares of Common Stock per Purchase Contract,

         in each case subject to adjustment as provided in the Purchase Contract
Agreement (and in each case rounded upward or downward to the nearest 1/10,000th
of a share).

         No fractional shares of Common Stock will be issued upon settlement of
Purchase Contracts, as provided in Section 5.09 of the Purchase Contract
Agreement.

         Each Purchase Contract evidenced hereby, which is settled either
through Early Settlement or Cash Settlement, shall obligate the Holder of the
related Treasury PEPS Unit to purchase at the Purchase Price for cash, and the
Company to sell, a number of shares of Common Stock equal to the Early
Settlement Rate or the Settlement Rate, as applicable.

         The "APPLICABLE MARKET VALUE" means the average of the Closing Prices
per share of

                                       B-5
<PAGE>   95

Common Stock on each of the 20 consecutive Trading Days ending on the third
Trading Day immediately preceding the Purchase Contract Settlement Date.

         The "CLOSING PRICE" per share of Common Stock on any date of
determination means the:

                  (1) closing sale price (or, if no closing price is reported,
         the last reported sale price) per share on the New York Stock Exchange,
         Inc. (the "NYSE") on such date;

                  (2) if the Common Stock is not listed for trading on the NYSE
         on any such date, the closing sale price per share as reported in the
         composite transactions for the principal United States securities
         exchange on which the Common Stock is so listed;

                  (3) if the Common Stock is not so listed on a United States
         national or regional securities exchange, the closing sale price per
         share as reported by The NASDAQ Stock Market, Inc.;

                  (4) if the Common Stock is not so reported, the last quoted
         bid price for the Common Stock in the over-the-counter market as
         reported by the National Quotation Bureau or similar organization; or

                  (5) if such bid price is not available, the average of the
         mid-point of the last bid and ask prices of the Common Stock on such
         date from at least three nationally recognized independent investment
         banking firms retained for this purpose by the Company.

         A "TRADING DAY" means a day on which the Common Stock (1) is not
suspended from trading on any national or regional securities exchange or
association or over-the-counter market at the close of business and (2) has
traded at least once on the national or regional securities exchange or
association or over-the-counter market that is the primary market for the
trading of the Common Stock.

         In accordance with the terms of the Purchase Contract Agreement, the
Holder of this Treasury PEPS Unit shall pay the Purchase Price for the shares of
the Common Stock purchased pursuant to each Purchase Contract evidenced hereby
either by effecting a Cash Settlement or an Early Settlement of each such
Purchase Contract or by applying a principal amount of the Pledged Treasury
Securities underlying such Holder's Treasury PEPS Unit equal to the Stated
Amount of such Purchase Contract to the purchase of the Common Stock. A Holder
of Treasury PEPS Unit who does not effect, prior to or on 11:00 a.m. (New York
City time) on the fifth Business Day immediately preceding the Purchase Contract
Settlement Date, an effective Cash Settlement or who does not effect on or prior
to 5 p.m. (New York City time) on the seventh Business Day prior to the Purchase
Contract Settlement Date an effective Early Settlement, shall pay the Purchase
Price for the shares of Common Stock to be issued under the related Purchase
Contract from the proceeds of the Pledged Treasury Securities.

                                       B-6
<PAGE>   96

         The Company shall not be obligated to issue any shares of Common Stock
in respect of a Purchase Contract or deliver any certificates therefor to the
Holder unless it shall have received payment of the aggregate purchase price for
the shares of Common Stock to be purchased thereunder in the manner herein set
forth.

         Each Purchase Contract evidenced hereby and all obligations and rights
of the Company and the Holder thereunder shall terminate if a Termination Event
shall occur. Upon the occurrence of a Termination Event, the Company shall give
written notice to the Purchase Contract Agent and to the Holders, at their
addresses as they appear in the Treasury PEPS Units Register. Upon and after the
occurrence of a Termination Event, the Collateral Agent shall release the
Pledged Treasury Securities (as defined in the Pledge Agreement) forming a part
of each Treasury PEPS Unit. A Treasury PEPS Unit shall thereafter represent the
right to receive the interest in the Treasury Security forming a part of such
Treasury PEPS Unit, in accordance with the terms of the Purchase Contract
Agreement and the Pledge Agreement.

         The Treasury PEPS Units Certificates are issuable only in registered
form and only in denominations of a single Treasury PEPS and any integral
multiple thereof. The transfer of any Treasury PEPS Certificate will be
registered and Treasury PEPS Certificates may be exchanged as provided in the
Purchase Contract Agreement. The Treasury PEPS Registrar may require a Holder,
among other things, to furnish appropriate endorsements and transfer documents
permitted by the Purchase Contract Agreement. No service charge shall be
required for any such registration of transfer or exchange, but the Company and
the Purchase Contract Agent may require payment of a sum sufficient to cover any
tax or other governmental charge payable in connection therewith. A Holder who
elects to substitute Preferred Securities or Senior Deferrable Notes, for
Treasury Securities, thereby recreating PEPS Units, shall be responsible for any
fees or expenses associated therewith. Except as provided in the Purchase
Contract Agreement, for so long as the Purchase Contract underlying a Treasury
PEPS Unit remains in effect, such Treasury PEPS Unit shall not be separable into
its constituent parts, and the rights and obligations of the Holder of such
Treasury PEPS Unit in respect of the Treasury Security and the Purchase Contract
constituting such Treasury PEPS Unit may be transferred and exchanged only as a
Treasury PEPS Unit.

         A Holder of Treasury PEPS Units may recreate PEPS Units by delivering
to the Collateral Agent, Preferred Securities or Senior Deferrable Notes with a
liquidation amount, in the case of such Preferred Securities or with a principal
amount in the case of such Senior Deferrable Notes, equal to the aggregate
principal amount at maturity of the Pledged Treasury Securities in exchange for
the release of such Pledged Treasury Securities in accordance with the terms of
the Purchase Contract Agreement and the Pledge Agreement. From and after such
substitution, the Holder's Security shall be referred to as a "PEPS UNIT". Any
such creation of PEPS Units may be effected in multiples of 40 Treasury PEPS
Units for 40 PEPS Units.

                                       B-7
<PAGE>   97

         A Holder of PEPS Units may recreate Treasury PEPS Units by delivering
to the Collateral Agent Treasury Securities in an aggregate principal amount
equal to the aggregate liquidation amount of the Pledged Preferred Securities or
the aggregate principal amount at maturity of the Pledged Senior Deferrable
Notes, as the case may be, in accordance with the terms of the Purchase Contract
Agreement and the Pledge Agreement. Any such recreation of Treasury PEPS Units
may be effected only in multiples of 40 PEPS Units for 40 Treasury PEPS Units.

         If a Tax Event Redemption has occurred, a Treasury PEPS Unit Holder may
not recreate PEPS Units, and a PEPS Unit Holder may not create a Treasury PEPS
Unit.

         The Purchase Contracts and all obligations and rights of the Company
and the Holders thereunder shall immediately and automatically terminate,
without the necessity of any notice or action by any Holder, the Purchase
Contract Agent or the Company, if, on or prior to the Purchase Contract
Settlement Date, a Termination Event shall have occurred. Upon the occurrence of
a Termination Event, the Company shall promptly but in no event later than two
Business Days thereafter give written notice to the Purchase Contract Agent, the
Collateral Agent and the Holders, at their addresses as they appear in the
Treasury PEPS Units Register. Upon and after the occurrence of a Termination
Event, the Collateral Agent shall release the Treasury Securities from the
Pledge in accordance with the provisions of the Pledge Agreement. A Treasury
PEPS Unit shall thereafter represent the right to receive the interest in the
Treasury Security forming a part of such Treasury PEPS Unit, in accordance with
the terms of the Purchase Contract Agreement and the Pledge Agreement.

         Subject to and upon compliance with the provisions of the Purchase
Contract Agreement, at the option of the Holder thereof, Purchase Contracts
underlying Securities may be settled early ("EARLY SETTLEMENT") as provided in
the Purchase Contract Agreement. In order to exercise the right to effect Early
Settlement with respect to any Purchase Contracts evidenced by this Treasury
PEPS Unit, the Holder of this Treasury PEPS Units Certificate shall deliver to
the Purchase Contract Agent at the Corporate Trust Office an Election to Settle
Early form set forth below and any other documents requested by the Purchase
Contract Agent duly completed and accompanied by payment in the form of
immediately available funds payable to the order of the Company in an amount
(the "EARLY SETTLEMENT AMOUNT") equal to the product of (A) $25 times (B) the
number of Purchase Contracts with respect to which the Holder has elected to
effect Early Settlement.

         Upon Early Settlement of Purchase Contracts by a Holder of the related
Securities, the Pledged Treasury Securities underlying such Securities shall be
released from the Pledge as provided in the Pledge Agreement and the Holder
shall be entitled to receive a number of shares of Common Stock on account of
each Purchase Contract forming part of a Treasury PEPS Unit as to which Early
Settlement is effected equal to .71531 shares of Common Stock per Purchase
Contract (the "EARLY SETTLEMENT RATE"). The Early Settlement Rate shall be
adjusted in the same manner and at the same time as the Settlement Rate is
adjusted as provided in the Purchase Contract Agreement.

                                       B-8
<PAGE>   98

         Upon registration of transfer of this Treasury PEPS Certificate, the
transferee shall be bound (without the necessity of any other action on the part
of such transferee, except as may be required by the Purchase Contract Agent
pursuant to the Purchase Contract Agreement), under the terms of the Purchase
Contract Agreement and the Purchase Contracts evidenced hereby and the
transferor shall be released from the obligations under the Purchase Contracts
evidenced by this Treasury PEPS Units Certificate. The Company covenants and
agrees, and the Holder, by its acceptance hereof, likewise covenants and agrees,
to be bound by the provisions of this paragraph.

         The Holder of this Treasury PEPS Units Certificate, by its acceptance
hereof, authorizes the Purchase Contract Agent to enter into and perform the
related Purchase Contracts forming part of the Treasury PEPS Units evidenced
hereby on its behalf as its attorney-in-fact, expressly withholds any consent to
the assumption (i.e., affirmance) of the Purchase Contracts by the Company or
its trustee in the event that the Company becomes the subject of a case under
the Bankruptcy Code, agrees to be bound by the terms and provisions thereof,
covenants and agrees to perform its obligations under such Purchase Contracts,
consents to the provisions of the Purchase Contract Agreement, authorizes the
Purchase Contract Agent to enter into and perform the Purchase Contract
Agreement and the Pledge Agreement on its behalf as its attorney-in-fact, and
consents to the Pledge of the Treasury Securities underlying this Treasury PEPS
Units Certificate pursuant to the Pledge Agreement. The Holder further covenants
and agrees, that, to the extent and in the manner provided in the Purchase
Contract Agreement and the Pledge Agreement, but subject to the terms thereof,
payments in respect to the aggregate principal amount of the Pledged Treasury
Securities on the Purchase Contract Settlement Date shall be paid by the
Collateral Agent to the Company in satisfaction of such Holder's obligations
under such Purchase Contract and such Holder shall acquire no right, title or
interest in such payments.

         Subject to certain exceptions, the provisions of the Purchase Contract
Agreement may be amended with the consent of the Holders of a majority of the
Purchase Contracts.

         The Purchase Contracts shall for all purposes be governed by, and
construed in accordance with, the laws of the State of New York.

         The Company, the Purchase Contract Agent and its Affiliates and any
agent of the Company or the Purchase Contract Agent may treat the Person in
whose name this Treasury PEPS Units Certificate is registered as the owner of
the Treasury PEPS Units evidenced hereby for the purpose of receiving payments
of interest on the Treasury Securities, performance of the Purchase Contracts
and for all other purposes whatsoever, whether or not any payments in respect
thereof be overdue and notwithstanding any notice to the contrary, and neither
the Company, the Purchase Contract Agent nor any such agent shall be affected by
notice to the contrary.

                                       B-9
<PAGE>   99

         The Purchase Contracts shall not, prior to the settlement thereof,
entitle the Holder to any of the rights of a holder of shares of Common Stock.

         A copy of the Purchase Contract Agreement is available for inspection
at the offices of the Purchase Contract Agent.

                                      B-10
<PAGE>   100

                                  ABBREVIATIONS

         The following abbreviations, when used in the inscription on the face
of this instrument, shall be construed as though they were written out in full
according to applicable laws or regulations:

TEN COM:                       as tenants in common

UNIF GIFT MIN ACT:             ___________________ Custodian ___________________
                                     (cust)                        (minor)
                               Under Uniform Gifts to Minors Act of
                                                                   -------------
                               -------------------------------------------------

TENANT:                        as tenants by the entireties

JT TEN:                        as joint tenants with right of survivorship and
                               not as tenants in common

Additional abbreviations may also be used though not in the above list.

                                   ----------

         FOR VALUE RECEIVED, the undersigned hereby sell(s), assign(s) and
transfer(s) unto

--------------------------------------------------------------------------------
      (Please insert Social Security or Taxpayer I.D. or other Identifying
                              Number of Assignee)

--------------------------------------------------------------------------------
  (Please Print or Type Name and Address Including Postal Zip Code of Assignee)

the within Treasury PEPS Units Certificates and all rights thereunder, hereby
irrevocably constituting and appointing __________________ attorney to transfer
said Treasury PEPS Units Certificates on the books of Valero Energy Corporation.
and VEC Trust I with full power of substitution in the premises.

Dated:
      ----------------------------     -----------------------------------------
                                       Signature

                                       NOTICE: The signature to this assignment
                                       must correspond with the name as it
                                       appears upon the face of the within
                                       Treasury PEPS Units Certificates in every
                                       particular, without alteration or
                                       enlargement or any change whatsoever.

         Signature Guarantee:
                             ---------------------------

                                      B-11
<PAGE>   101

                             SETTLEMENT INSTRUCTIONS

         The undersigned Holder directs that a certificate for shares of Common
Stock deliverable upon settlement on or after the Purchase Contract Settlement
Date of the Purchase Contracts underlying the number of Treasury PEPS Units
evidenced by this Treasury PEPS Units Certificate be registered in the name of,
and delivered, together with a check in payment for any fractional share, to the
undersigned at the address indicated below unless a different name and address
have been indicated below. If shares are to be registered in the name of a
Person other than the undersigned, the undersigned will pay any transfer tax
payable incident thereto.

Dated:
      ----------------------------     -----------------------------------------
                                       Signature

                                       Signature Guarantee:
                                                           ---------------------
                                       (if assigned to another person)

If shares are to be registered in
the name of and delivered to a         REGISTERED HOLDER
Person other than the Holder,
please (i) print such Person's name
and address and (ii) provide a
guarantee of your signature:           Please print name and address of
                                       Registered Holder:

----------------------------------     -----------------------------------------
Name                                   Name

----------------------------------     -----------------------------------------
Address                                Address

----------------------------------     -----------------------------------------

----------------------------------     -----------------------------------------

----------------------------------     -----------------------------------------

Social Security or other
Taxpayer Identification
Number, if any
                                       -----------------------------------------

                                      B-12
<PAGE>   102

                            ELECTION TO SETTLE EARLY

         The undersigned Holder of this Treasury PEPS Units Certificate
irrevocably exercises the option to effect Early Settlement in accordance with
the terms of the Purchase Contract Agreement with respect to the Purchase
Contracts underlying the number of Treasury PEPS Units evidenced by this
Treasury PEPS Units Certificate specified below. The option to effect Early
Settlement may be exercised only with respect to Purchase Contracts underlying
Treasury PEPS with an aggregate Stated Amount equal to $1,000 or an integral
multiple thereof. The undersigned Holder directs that a certificate for shares
of Common Stock deliverable upon such Early Settlement be registered in the name
of, and delivered, together with a check in payment for any fractional share and
any Treasury PEPS Units Certificate representing any Treasury PEPS Units
evidenced hereby as to which Early Settlement of the related Purchase Contracts
is not effected, to the undersigned at the address indicated below unless a
different name and address have been indicated below. Pledged Treasury
Securities deliverable upon such Early Settlement will be transferred in
accordance with the transfer instructions set forth below. If shares are to be
registered in the name of a Person other than the undersigned, the undersigned
will pay any transfer tax payable incident thereto.

Dated:
      -----------------------          -----------------------------------------
                                       Signature

Signature Guarantee:
                    -----------------------------

                                      B-13
<PAGE>   103

         Number of Securities evidenced hereby as to which Early Settlement of
the related Purchase Contracts is being elected:

If shares of Common Stock of           REGISTERED HOLDER
Treasury PEPS Units Certificates
are to be registered in the name
of and delivered to and Pledged
Treasury Securities are to be
transferred to a Person other than
the Holder, please print such
Person's name and address:

                                       Please print name and address of
                                       Registered Holder:

----------------------------------     -----------------------------------------
              Name                                        Name

----------------------------------     -----------------------------------------
             Address                                     Address

----------------------------------     -----------------------------------------
----------------------------------     -----------------------------------------
----------------------------------     -----------------------------------------

Social Security or other
Taxpayer Identification
Number, if any
                                       -----------------------------------------

Transfer Instructions for Pledged Treasury Securities Transferable Upon Early
Settlement or a Termination Event:

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------

                                      B-14
<PAGE>   104

                     [TO BE ATTACHED TO GLOBAL CERTIFICATES]

            SCHEDULE OF INCREASES OR DECREASES IN GLOBAL CERTIFICATE

The following increases or decreases in this Global Certificate have been made:

<TABLE>
<CAPTION>
=======================================================================================================================
                                                                          Number of Treasury
                         Amount of increase in   Amount of decrease in   PEPS Units evidenced
                          Number of Treasury      Number of Treasury        by this Global
                         PEPS Units evidenced    PEPS Units evidenced    Certificate following  Signature of authorized
                             by the Global           by the Global         such decrease or     officer of Trustee or
Date                          Certificate             Certificate              increase         Securities Custodian
<S>                      <C>                     <C>                     <C>                    <C>

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------
</TABLE>

                                      B-15
<PAGE>   105

                                                                       EXHIBIT C

                     INSTRUCTION TO PURCHASE CONTRACT AGENT

Bank of New York
101 Barclay Street
21 West
New York, New York 10286
Attention: Corporate Trust Trustee Administration

         Re: [_______ PEPS Units] [_______ Treasury PEPS Units] of Valero Energy
Corporation, a Delaware corporation (the "COMPANY") and VEC Trust I.

         The undersigned Holder hereby notifies you that it has delivered to
Bank One Trust Company, N.A., as Securities Intermediary, for credit to the
Collateral Account, $______ aggregate [principal] [liquidation] amount of
[Preferred Securities] [Senior Deferrable Notes] [Treasury Securities] in
exchange for the [Pledged Preferred Securities] [Pledged Senior Deferrable
Notes] [Pledged Treasury Securities] held in the Collateral Account, in
accordance with the Pledge Agreement, dated as of June 28, 2000 (the "PLEDGE
AGREEMENT"; unless otherwise defined herein, terms defined in the Pledge
Agreement are used herein as defined therein), between you, the Company, the
Collateral Agent and the Securities Intermediary. The undersigned Holder has
paid all applicable fees relating to such exchange. The undersigned Holder
hereby instructs you to instruct the Collateral Agent to release to you on
behalf of the undersigned Holder the [Pledged Preferred Securities] [Pledged
Senior Deferrable Notes] [Pledged Treasury Securities] related to such [PEPS
Units] [Treasury PEPS Units].

Date:
     ------------------------          -----------------------------------------
                                       Signature

                             Signature Guarantee:
                                                 -------------------------------
<PAGE>   106
Please print name and address of Registered Holder:

----------------------------------     -----------------------------------------
Name                                   Social Security or other Taxpayer
                                       Identification Number, if any

Address

----------------------------------

----------------------------------

----------------------------------

----------------------------------

                                      C-2
<PAGE>   107

                                                                       EXHIBIT D

                       NOTICE FROM PURCHASE CONTRACT AGENT
                                   TO HOLDERS
         (Transfer of Collateral upon Occurrence of a Termination Event)

[HOLDER]

-----------------------------

-----------------------------
Attention:
Telecopy:
          ----------

                  Re:      [__________ PEPS Units] [______ Treasury PEPS Units]
                           of Valero Energy Corporation, a Delaware corporation
                           (the "COMPANY") and VEC Trust I

         Please refer to the Purchase Contract Agreement, dated as of June 28,
2000 (the "PURCHASE CONTRACT AGREEMENT"; unless otherwise defined herein, terms
defined in the Purchase Contract Agreement are used herein as defined therein),
between the Company and the undersigned, as Purchase Contract Agent and as
attorney-in-fact for the holders of PEPS Units and Treasury PEPS Units from time
to time.

         We hereby notify you that a Termination Event has occurred and that
[the Senior Deferrable Notes][the Treasury Securities] underlying your ownership
interest in _____ [PEPS Units] [Treasury PEPS Units] have been released and are
being held by us for your account pending receipt of transfer instructions with
respect to such [Senior Deferrable Notes][Treasury Securities] (the "RELEASED
SECURITIES").

         Pursuant to Section 3.15 of the Purchase Contract Agreement, we hereby
request written transfer instructions with respect to the Released Securities.
Upon receipt of your instructions and upon transfer to us of your [PEPS
Units][Treasury PEPS Units] effected through book-entry or by delivery to us of
your [PEPS Units Certificate][Treasury PEPS Units Certificate], we shall
transfer the Released Securities by book-entry transfer or other appropriate
procedures, in accordance with your instructions. In the event you fail to
effect such transfer or delivery, the Released Securities and any distributions
thereon, shall be held in our name, or a nominee in trust for your benefit,
until such time as such [PEPS Units][Treasury PEPS Units] are transferred or
your [PEPS Units Certificate] [Treasury PEPS Units Certificate] is surrendered
or satisfactory evidence is provided that such [PEPS Units Certificate][Treasury
PEPS Units Certificate] has been destroyed, lost or stolen, together with any
indemnification that we or the Company may require.

<PAGE>   108

Date:                                  By: THE BANK OF NEW YORK

                                       -----------------------------------------
                                       Name:
                                       Title: Authorized Signatory

                                      D-2
<PAGE>   109

                                                                       EXHIBIT E

                            NOTICE TO SETTLE BY CASH

The Bank of New York
101 Barclay Street
21 West
New York, New York 10286
Attention: Corporate Trust Trustee Administration

                  Re:      [_______ PEPS Units] [Treasury PEPS Units] of Valero
                           Energy Corporation, a Delaware corporation (the
                           "COMPANY") and VEC Trust I

         The undersigned Holder hereby irrevocably notifies you in accordance
with Section 5.02 of the Purchase Contract Agreement, dated as of June 28, 2000
(the "PURCHASE CONTRACT AGREEMENT"; unless otherwise defined herein, terms
defined in the Purchase Contract Agreement are used herein as defined therein),
between the Company and you, as Purchase Contract Agent and as Attorney-in-Fact
for the Holders of the Purchase Contracts, that such Holder has elected to pay
to the Securities Intermediary for deposit in the Collateral Account, prior to
or on 11:00 a.m. (New York City time) on the fifth Business Day immediately
preceding the Purchase Contract Settlement Date (in lawful money of the United
States by certified or cashiers' check or wire transfer, in immediately
available funds), $______ as the Purchase Price for the shares of Common Stock
issuable to such Holder by the Company under the related Purchase Contracts on
the Purchase Contract Settlement Date. The undersigned Holder hereby instructs
you to notify promptly the Collateral Agent of the undersigned Holders' election
to make such cash settlement with respect to the Purchase Contracts related to
such Holder's [PEPS Units] [Treasury PEPS Units].

Date:
     -----------------------------     -----------------------------------------
                                       Signature

                                       Signature Guarantee:
                                                           ---------------------

Please print name and address of Registered Holder:

                                      E-1
<PAGE>   110

                                                                       EXHIBIT F

                       NOTICE FROM PURCHASE CONTRACT AGENT
                    TO COLLATERAL AGENT AND INDENTURE TRUSTEE
              (Settlement of Purchase Contract through Remarketing)

Bank One Trust Company, N.A.
One North State Street, 9th Floor
Chicago, Illinois 60670-0126
Attention: Corporate Trust Administration
Telecopy: (312) 407-1708

The Bank of New York
101 Barclay Street
21 West
New York, New York 10286
Attention: Corporate Trust Trustee Administration
Telecopy: (212) 815-5915

                  Re:      __________ PEPS Units of Valero Energy Corporation, a
                           Delaware corporation (the "COMPANY") and VEC Trust I

         Please refer to the Purchase Contract Agreement, dated as of June 28,
2000 (the "PURCHASE CONTRACT AGREEMENT"; unless otherwise defined herein, terms
defined in the Purchase Contract Agreement are used herein as defined therein),
between the Company and the undersigned, as Purchase Contract Agent and as
attorney-in-fact for the Holders of PEPS Units from time to time.

         In accordance with Section 5.02 of the Purchase Contract Agreement and,
based on instructions and Cash Settlements received from Holders of PEPS Units
as of 11:00 a.m. (New York City time), the fifth Business Day preceding the
Purchase Contract Settlement Date, we hereby notify you that ______ [Preferred
Securities] [Senior Deferrable Notes] are to be tendered for purchase in the
Remarketing.

Date:                                  By: THE BANK OF NEW YORK

                                       -----------------------------------------
                                       Name:
                                       Title: Authorized Officer

                                      F-1

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