<PAGE>

                                                                    EXHIBIT 4.19

                                                                            FORM

                              [Subordinated Notes]

                                   ONEOK, INC.

                                       AND

                              ____________________,

                      As Collateral Agent, Custodial Agent
                           And Securities Intermediary

                                       AND

                                 SUNTRUST BANK,

                           As Purchase Contract Agent

                                   ----------

                                PLEDGE AGREEMENT

                                   ----------

                         DATED AS OF ________ ___, ____

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                                TABLE OF CONTENTS

                                                                            PAGE

ARTICLE I    Definitions...................................................... 2

     SECTION 1.01.      Definitions........................................... 2

ARTICLE II   The Pledge....................................................... 6

     SECTION 2.01.      The Pledge............................................ 6

     SECTION 2.02.      Control............................................... 7

     SECTION 2.03.      Termination........................................... 8

ARTICLE III  Distributions on Pledged Collateral.............................. 9

     SECTION 3.01.      Income and Distributions.............................. 9

     SECTION 3.02.      Principal Payments Following Termination Event........ 9

     SECTION 3.03.      Principal Payments Prior to or on Purchase Contract
                        Settlement Date....................................... 9

     SECTION 3.04.      Payments to Purchase Contract Agent...................10

     SECTION 3.05.      Assets Not Properly Released..........................10

ARTICLE IV   Initial Deposit; Creation of Treasury Units and Recreation of
             Corporate Units..................................................10

     SECTION 4.01.      Initial Deposit of Subordinated Notes.................10

     SECTION 4.02.      Creation of Treasury Units............................11

     SECTION 4.03.      Recreation of Corporate Units.........................12

     SECTION 4.04.      Termination Event.....................................13

     SECTION 4.05.      Cash Settlement.......................................14

     SECTION 4.06.      Early Settlement and Cash Merger Early Settlement.....15

     SECTION 4.07.      Application of Proceeds in Settlement of Purchase
                        Contracts.............................................16

ARTICLE V    Voting Rights Pledged Subordinated Notes.........................18

     SECTION 5.01.      Voting Rights.........................................18

ARTICLE VI   Rights and Remedies..............................................19

     SECTION 6.01.      Rights and Remedies of the Collateral Agent...........19

     SECTION 6.02.      Special Event Redemption..............................20

     SECTION 6.03.      Successful Initial Remarketing........................20

     SECTION 6.04.      Substitutions.........................................21

ARTICLE VII  Representations and Warranties; Covenants........................21

     SECTION 7.01.      Representations and Warranties........................21

<PAGE>

                                TABLE OF CONTENTS
                                   (continued)
                                                                            Page

     SECTION 7.02.      Covenants.............................................22

ARTICLE VIII The Collateral Agent, the Custodial Agent and the Securities
             Intermediary.....................................................22

     SECTION 8.01.      Appointment, Powers and Immunities....................22

     SECTION 8.02.      Instructions of the Company...........................23

     SECTION 8.03.      Reliance by Collateral Agent and Securities
                        Intermediary..........................................24

     SECTION 8.04.      Certain Rights........................................24

     SECTION 8.05.      Merger, Conversion, Consolidation or Succession to
                        Business..............................................24

     SECTION 8.06.      Rights in Other Capacities............................25

     SECTION 8.07.      Non-reliance on Collateral Agent, the Custodial Agent
                        and Securities Intermediary...........................25

     SECTION 8.08.      Compensation and Indemnity............................25

     SECTION 8.09.      Failure to Act........................................26

     SECTION 8.10.      Resignation of Collateral Agent, the Custodial Agent
                        and Securities Intermediary...........................27

     SECTION 8.11.      Right to Appoint Agent or Advisor.....................28

     SECTION 8.12.      Survival..............................................28

     SECTION 8.13.      Exculpation...........................................28

ARTICLE IX   Amendment........................................................29

     SECTION 9.01.      Amendment Without Consent of Holders..................29

     SECTION 9.02.      Amendment with Consent of Holders.....................29

     SECTION 9.03.      Execution of Amendments...............................30

     SECTION 9.04.      Effect of Amendments..................................30

     SECTION 9.05.      Reference of Amendments...............................30

ARTICLE X    Miscellaneous....................................................31

     SECTION 10.01.     No Waiver.............................................31

     SECTION 10.02.     Governing Law; Submission to Jurisdiction.............31

     SECTION 10.03.     Notices...............................................31

     SECTION 10.04.     Successors and Assigns................................32

     SECTION 10.05.     Counterparts..........................................32

     SECTION 10.06.     Severability..........................................32

                                       ii

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                                TABLE OF CONTENTS
                                   (continued)
                                                                            Page

     SECTION 10.07.     EXPENSES, ETC.........................................32

     SECTION 10.08.     Security Interest Absolute............................33

     SECTION 10.09.     Notice of Special Event, Special Event Redemption and
                        Termination Event.....................................33

EXHIBITS

Exhibit A - Instruction from Purchase Contract Agent to Collateral Agent
(Creation of Treasury Units)
Exhibit B - Instruction from Collateral Agent to Securities Intermediary
(Creation of Treasury Units)
Exhibit C - Instruction from Purchase Contract Agent to Collateral Agent
(Recreation of Corporate Units)
Exhibit D - Instruction from Collateral Agent to Securities Intermediary
(Recreation of Corporate Units)
Exhibit E - Notice of Cash Settlement from Collateral Agent to Purchase Contract
Agent
Exhibit F - Instruction to Custodial Agent Regarding Remarketing
Exhibit G - Instruction to Custodial Agent Regarding Withdrawal From Remarketing

                                       iii

<PAGE>

                                PLEDGE AGREEMENT

          PLEDGE AGREEMENT, dated as of ________ ___, ____, among ONEOK, Inc., a
Delaware corporation (the "Company"), ______________, not individually, but
solely as collateral agent (in such capacity, together with its successors in
such capacity, the "Collateral Agent"), as custodial agent (in such capacity,
together with its successors in such capacity, the "Custodial Agent"), and as
securities intermediary (as defined in Sections 8-102(a)(14) of the UCC) with
respect to the Collateral Account (in such capacity, together with its
successors in such capacity, the "Securities Intermediary"), and SunTrust Bank,
not individually, but solely as purchase contract agent, attorney-in-fact and
trustee for the Holders (as defined in the Purchase Contract Agreement) from
time to time of the Units (as hereinafter defined) (in any one or more of such
capacities, together with its successors in such capacity, the "Purchase
Contract Agent") under the Purchase Contract Agreement (as hereinafter defined).

                                    RECITALS

          WHEREAS, the Company and the Purchase Contract Agent are parties to
the Purchase Contract Agreement dated as of the date hereof (as modified and
supplemented and in effect from time to time, the "Purchase Contract
Agreement"), pursuant to which there may be issued up to ___________ Corporate
Units (as hereinafter defined) (or ___________ if the underwriters exercise
their over-allotment option in full) will be issued.

          WHEREAS, the Units will initially consist of (A) ___________ (or
__________ if the underwriters exercise their over-allotment option in full)
units (referred to as "Corporate Units") with a stated amount per Corporate Unit
of $_____ (the "Stated Amount"). Each Corporate Unit will consist of (a) a stock
purchase contract (a "Purchase Contract") for the purchase of shares of the
Company's common stock, $0.01 par value per share ("Common Stock"), and (b)
initially, a Subordinated note due ________ ___, ____ (a "Subordinated Note",
which will be issued pursuant to an Indenture, dated as of ________ ___, ____,
between the Company and SunTrust Bank, as trustee (the "Indenture Trustee")
(said Indenture, together with any amendments or supplements thereto being
hereinafter referred to as the "Indenture") and a supplemental indenture
establishing the terms of the Subordinated Notes to be dated on or about
________ ___, ____, in each case, with the material terms described in the
Prospectus (as hereinafter defined)). Holders of Corporate Units shall be
entitled to substitute Treasury Securities for the Subordinated Notes that
comprise the Corporate Units (as so substituted, the "Treasury Units"). Each
Treasury Unit will consist of (a) a Purchase Contract and (b) zero-coupon U.S.
Treasury securities (CUSIP No. _________), each in a principal amount equal to
$_________, payable on ________ ___, ____ (each such Treasury security being
hereinafter referred to as a "Treasury Security").

          WHEREAS, pursuant to the terms of the Purchase Contract Agreement and
the Purchase Contracts, the Holders, from time to time, of the Units have
irrevocably authorized the Purchase Contract Agent, as attorney-in-fact of such
Holders, among other things, to execute and deliver this Agreement on behalf of
such Holders and to grant the pledge provided hereby of the Subordinated Notes,
any Applicable Ownership Interest in the Treasury Portfolio (as specified in
clause (i) of the definition of such term) and any Treasury Securities to secure
each Holder's obligations under the related Purchase Contract, as provided
herein and subject to the terms

<PAGE>

hereof. Upon such pledge, the Subordinated Notes will be beneficially owned by
the Holders but will be owned of record by the Purchase Contract Agent, on its
own behalf and as attorney-in-fact and trustee for the Holders from time to time
of the Units, subject to the Pledge hereunder.

          NOW, THEREFORE, the Company, the Collateral Agent, the Custodial
Agent, the Securities Intermediary and the Purchase Contract Agent agree as
follows:

                                    ARTICLE I

                                   DEFINITIONS

          SECTION 1.01   Definitions.

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

          (a)  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;

          (b)  the following terms which are defined in the UCC shall have the
meanings set forth therein: "certificated security," "control," "financial
asset," "entitlement order," "securities account" and "security entitlement";

          (c)  capitalized terms used herein and not defined herein have the
meanings assigned to them in the Purchase Contract Agreement; and

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

               "Agreement" means this Pledge Agreement, as the same may from
time to time be amended, modified or supplemented.

               "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.

               "Business Day" means any day other than a Saturday, Sunday or any
other day on which banking institutions in the City of New York (in the State of
New York) are permitted or required by applicable law to close.

               "Cash" means any coin or currency of the United States as at the
time shall be legal tender for payment of public and private debts.

               "Collateral" has the meaning specified in Section 2.01 hereof.

               "Collateral Account" means the securities account of ___________,
as Collateral Agent, maintained by the Securities Intermediary and designated
"____________ as Collateral Agent of ONEOK, Inc., as pledgee of SunTrust Bank,
as the Purchase Contract Agent, attorney-in-fact and trustee for the Holders."

                                        2

<PAGE>

               "Collateral Agent" has the meaning specified in the paragraph
preceding the Recitals of this Agreement.

               "Common Stock" has the meaning specified in the Recitals.

               "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 provisions of the Purchase Contract Agreement, and thereafter
"Company" shall mean such successor.

               "Corporate Unit" means the collective rights and obligations of a
Holder of a Corporate Units Certificate in respect of a Subordinated Note or an
appropriate Applicable Ownership Interests in 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 Interests
(as specified in clause (ii) of the definition of such term) in the Treasury
Portfolio shall not be subject to the Pledge.

               "Corporate Units Certificate" means a certificate evidencing the
rights and obligations of a Holder in respect of the number of Corporate Units
specified on such certificate.

               "Custodial Agent" has the meaning specified in the paragraph
preceding the Recitals of this Agreement.

               "Indenture" has the meaning specified in the Recitals.

               "Indenture Trustee" has the meaning specified in the Recitals.

               "Obligations" means, with respect to each Holder, all obligations
and liabilities of such Holder under such Holder's Purchase Contract, the
Purchase Contract Agreement and this Agreement or any other document made,
delivered or given in connection herewith or therewith, in each case whether on
account of principal, interest (including, without limitation, interest accruing
before and after the filing of any petition in bankruptcy, or the commencement
of any insolvency, reorganization or like proceeding, relating to such Holder,
whether or not a claim for post-filing or post-petition interest is allowed in
such proceeding), fees, indemnities, costs, expenses or otherwise (including,
without limitation, all fees and disbursements of counsel to the Company or the
Collateral Agent or the Securities Intermediary that are required to be paid by
the Holder pursuant to the terms of any of the foregoing agreements).

               "Permitted Investments" means any one of the following, in each
case maturing on the Business Day following the date of acquisition:

               (i)     any evidence of indebtedness with an original maturity of
          365 days or less issued, or directly and fully guaranteed or insured,
          by the United States of America or any agency or instrumentality
          thereof (provided that the full faith and credit of the United States
          of America is pledged in support of the timely payment thereof or such
          indebtedness constitutes a general obligation of it);

               (ii)    deposits, certificates of deposit or acceptances with an
          original maturity of 365 days or less of any institution which is a
          member of the Federal Reserve System

                                        3

<PAGE>

          having combined capital and surplus and undivided profits of not less
          than $200 million at the time of deposit as of the date of its latest
          filed report of condition or its audited financial statements;

               (iii)   investments with an original maturity of 365 days or less
          of any Person that is fully and unconditionally guaranteed by a bank
          referred to in clause (ii);

               (iv)    repurchase agreements and reverse repurchase agreements
          relating to marketable direct obligations issued or unconditionally
          guaranteed by the United States of America or issued by any agency
          thereof and backed as to timely payment by the full faith and credit
          of the United States of America;

               (v)     investments in commercial paper, other than commercial
          paper issued by the Company or its affiliates, of any corporation
          incorporated under the laws of the United States or any State thereof,
          which commercial paper has a rating at the time of purchase at least
          equal to "A-1" by Standard & Poor's Ratings Services ("S&P") or at
          least equal to "P-1" by Moody's Investors Service, Inc. ("Moody's");
          and

               (vi)    investments in money market funds (including, but not
          limited to, money market funds managed by the Collateral Agent or an
          affiliate of the Collateral Agent) registered under the Investment
          Company Act of 1940, as amended, rated in the highest applicable
          rating category by S&P or Moody's.

               "Person" means any legal person, including, without limitation,
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.

               "Pledge" means the lien and security interest created by this
Agreement.

               "Pledged Applicable Ownership Interests" means the Applicable
Ownership Interests (as specified in clause (i) of the definition thereof) of
the Holders with respect to the Treasury Portfolio and security entitlements
with respect thereto from time to time credited to the Collateral Account and
not then released from the Pledge.

               "Pledged Subordinated Notes" means Subordinated Notes and
security entitlements with respect thereto from time to time credited to the
Collateral Account and not then released from the Pledge.

               "Pledged Securities" means the Pledged Subordinated Notes, the
Pledged Applicable Ownership Interests and the Pledged Treasury Securities,
collectively.

               "Pledged Treasury Securities" means Treasury Securities and
security entitlements with respect thereto from time to time credited to the
Collateral Account and not then released from the Pledge.

               "Proceeds" means all interest, dividends, cash, instruments,
securities, financial assets (as defined in Section 8-102(a)(9) of the UCC) and
other property from time to time

                                        4

<PAGE>

received, receivable or otherwise distributed upon the sale, exchange,
collection or disposition of any financial assets from time to time held in the
Collateral Account.

               "Purchase Contract" has the meaning specified in the Recitals.

               "Purchase Contract Agent" has the meaning specified in the
paragraph preceding the Recitals of this Agreement.

               "Purchase Contract Agreement" has the meaning specified in the
Recitals.

               "Securities Intermediary" has the meaning specified in the
paragraph preceding the Recitals of this Agreement.

               "Separate Subordinated Notes" means Subordinated Notes which are
not components of Corporate Units.

               "Stated Amount" has the meaning specified in the Recitals.

               "TRADES" means the Treasury/Reserve Automated Debt Entry System
maintained by the Federal Reserve Bank of New York pursuant to the TRADES
Regulations.

               "TRADES Regulations" means the regulations of the United States
Department of the Treasury, published at 31 C.F.R. Part 357, as amended from
time to time. Unless otherwise defined herein, all terms defined in the TRADES
Regulations are used herein as therein defined.

               "Transfer" means (i) in the case of certificated securities in
registered form, delivery as provided in Section 8-301(a) of the UCC, indorsed
to the transferee or in blank by an effective endorsement; (ii) in the case of
Treasury Securities, registration of the transferee as the owner of such
Treasury Securities on TRADES; and (iii) in the case of security entitlements,
including, without limitation, security entitlements with respect to Treasury
Securities, a securities intermediary indicating by book entry that such
security entitlement has been credited to the transferee's securities account.

               "Treasury Securities" means zero-coupon U.S. treasury securities
(CUSIP No. __________) which are the principal strips of the U.S. treasury
securities that mature on ________ ___, ____.

               "Treasury Unit" means, following the substitution of Treasury
Securities for Subordinated Notes as collateral to secure a Holder's
Obligations, the collective rights and obligations of a Holder of a Treasury
Units Certificate in respect of such Treasury Securities, subject to the Pledge
thereof, and the related Purchase Contract.

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

               "UCC" means the Uniform Commercial Code as in effect in the State
of New York from time to time.

                                        5

<PAGE>

               "Value" means, with respect to any item of Collateral on any
date, as to (i) Cash, the face amount thereof, (ii) Treasury Securities or
Subordinated Notes, the aggregate principal amount thereof at maturity and (iii)
Applicable Ownership Interests (as specified in clause (i) of the definition of
such term), the appropriate percentage of the aggregate principal amount at
maturity of the Treasury Portfolio.

                                   ARTICLE II

                                   THE PLEDGE

          SECTION 2.01.  The Pledge.

          The Holders from time to time acting through the Purchase Contract
Agent, as their attorney-in-fact, as their trustee and as the Purchase Contract
Agent, acting solely as such attorney-in-fact, hereby pledge and grant to the
Collateral Agent, as agent of and for the benefit of the Company, a continuing
first priority security interest in and to, and a lien upon and right of set off
against (i) all of such Person's right, title and interest in and to (a) the
Collateral to secure the prompt and complete payment and performance when due
(whether at stated maturity, by acceleration or otherwise) of the Obligations
from time to time; (b) the Applicable Ownership Interests (as specified in
clause (i) of the definition of such term); (c) any Treasury Securities and
security entitlements relating thereto delivered from time to time upon creation
of Treasury Units in accordance with Section 4.02; (d) payments made by Holders
pursuant to Section 4.05; (e) the Collateral Account and all securities,
financial assets, Cash and other property credited thereto and all security
entitlements related thereto; and (f) all Proceeds of the foregoing (whether
such Proceeds arise before or after the commencement of any proceeding under any
applicable bankruptcy, insolvency or other similar law, by or against the
pledgor or with respect to the pledgor) (all of the foregoing, collectively, the
"Collateral") and (ii) all powers and rights now owned or hereafter acquired
under or with respect to the Collateral.

          Prior to or concurrently with the execution and delivery of this
Agreement, the Purchase Contract Agent, on behalf of the initial Holders of the
Units, shall cause the Subordinated Notes or the Applicable Ownership Interests
(as specified in clause (i) of the definition of such term), as the case may be,
comprising a part of the Corporate Units, and the Treasury Securities comprising
a part of the Treasury Units, to be Transferred to the Collateral Agent for the
benefit of the Company. Such Subordinated Notes or the Applicable Ownership
Interests (as specified in clause (i) of the definition of such term), as the
case may be, shall be Transferred by physically delivering such Subordinated
Notes or the Applicable Ownership Interests (as specified in clause (i) of the
definition of such term), as the case may be, to the Collateral Agent endorsed
in blank. Treasury Securities and the Treasury Portfolio, as applicable, shall
be Transferred to the Collateral Account maintained by the Collateral Agent at
the Securities Intermediary by book-entry transfer to the Collateral Account in
accordance with the TRADES Regulations and other applicable law and by the
notation by the Securities Intermediary on its books that a security entitlement
with respect to such Treasury Securities or Treasury Portfolio, has been
credited to the Collateral Account. For purposes of perfecting the Pledge under
applicable law, including, to the extent applicable, the TRADES Regulations or
the UCC, as adopted and in effect in any applicable jurisdiction, the Collateral
Agent shall be the agent of the Company as provided herein. Subject to the
Pledge and the provisions of Section 2.02 hereof,

                                        6

<PAGE>

the Holders from time to time shall have full beneficial ownership of the
Collateral. The Collateral Agent shall have the right to have the Subordinated
Notes or any other Units held in physical form.

          Except as may be required in order to release Subordinated Notes, the
Applicable Ownership Interests (as specified in clause (i) of the definition of
such term) or Treasury Securities in connection with a Holder's election to
convert its investment from Corporate Units to Treasury Units, as the case may
be, or except as otherwise required to release Pledged Securities as specified
herein, neither the Collateral Agent nor the Securities Intermediary shall
relinquish physical possession of any certificate evidencing Subordinated Notes,
the Applicable Ownership Interests (as specified in clause (i) of the definition
of such term), as the case may be, or Treasury Securities prior to the
termination of this Agreement. If it becomes necessary for the Collateral Agent
to relinquish physical possession of a certificate in order to release a portion
of the Subordinated Notes or the Applicable Ownership Interests (as specified in
clause (i) of the definition of such term), as the case may be, or the Treasury
Securities evidenced thereby from the Pledge, the Collateral Agent shall use its
best efforts to obtain physical possession of a replacement certificate
evidencing any Subordinated Notes or the Applicable Ownership Interests (as
specified in clause (i) of the definition of such term), as the case may be, or
the Treasury Securities remaining subject to the Pledge hereunder registered to
it or endorsed in blank within ten days of the date it relinquished possession.
The Collateral Agent shall promptly notify the Company of its failure to obtain
possession of any such replacement certificate as required hereby.

          SECTION 2.02.  Control.

          (a)  In connection with the Pledge granted in Section 2.01, and
subject to the other provisions of this Agreement, the Holders from time to time
acting through the Purchase Contract Agent, as their attorney-in-fact, hereby
authorize and direct the Securities Intermediary (without the necessity of
obtaining the further consent of the Purchase Contract Agent or any of the
Holders), and the Securities Intermediary agrees, to comply with and follow any
instructions and entitlement orders (as defined in Section 8-102(a)(8) of the
UCC) that the Collateral Agent on behalf of the Company may give in writing with
respect to the Collateral Account, the Collateral credited thereto and any
security entitlements with respect to any thereof. Such instructions and
entitlement orders may, without limitation, direct the Securities Intermediary
to transfer, redeem, sell, liquidate, assign, deliver or otherwise dispose of
the Subordinated Notes, the Treasury Securities, the Treasury Portfolio, and any
security entitlements with respect thereto and to pay and deliver any income,
proceeds or other funds derived therefrom to the Company. The Purchase Contract
Agent and the Holders from time to time, acting through the Purchase Contract
Agent, each hereby further authorize and direct the Collateral Agent, as Agent
of the Company, to itself issue instructions and entitlement orders, and to
otherwise take action, with respect to the Collateral Account, the Collateral
credited thereto and any security entitlements with respect thereto, pursuant to
the terms and provisions hereof, all without the necessity of obtaining the
further consent of the Purchase Contract Agent or any of the Holders. The
Collateral Agent shall be the Agent of the Company and shall act as directed in
writing by the Company. Without limiting the generality of the foregoing, the
Collateral Agent shall issue entitlement orders to the Securities Intermediary
when and as directed in writing by the Company.

                                        7

<PAGE>

          (b)  The Securities Intermediary hereby confirms and agrees that: (i)
all securities or other property underlying any financial assets credited to the
Collateral Account shall be registered in the name of the Securities
Intermediary, indorsed to the Securities Intermediary or in blank or credited to
another Collateral Account maintained in the name of the Securities Intermediary
and in no case will any financial asset credited to the Collateral Account be
registered in the name of the Purchase Contract Agent, the Company or any
Holder, payable to the order of, or specially indorsed to, the Purchase Contract
Agent, the Collateral Agent, the Company or any Holder except to the extent the
foregoing have been specially indorsed to the Securities Intermediary or in
blank; (ii) all property delivered to the Securities Intermediary pursuant to
this Pledge Agreement (including, without limitation, any Subordinated Notes,
the Treasury Portfolio or Treasury Securities) will be promptly credited to the
Collateral Account; (iii) the Collateral Account is an account to which
financial assets are or may be credited, and the Securities Intermediary shall,
subject to the terms of this Agreement, treat the Purchase Contract Agent as
entitled to exercise the rights of any financial asset credited to the
Collateral Account; (iv) the Securities Intermediary has not entered into, and
until the termination of the this Agreement will not enter into, any agreement
with any other Person relating to the Collateral Account and/or any financial
assets credited thereto pursuant to which it has agreed to comply with
entitlement orders (as defined in Section 8-102(a)(8) of the UCC) of such other
Person; and (vi) the Securities Intermediary has not entered into, and until the
termination of this Agreement will not enter into, any agreement with the
Company, the Collateral Agent or the Purchase Contract Agent purporting to limit
or condition the obligation of the Securities Intermediary to comply with
entitlement orders as set forth in this Section 2.02 hereof.

          (c)  The Securities Intermediary hereby agrees that each item of
property (whether investment property, financial asset, security, instrument or
cash) credited to the Collateral Account shall be treated as a "financial asset"
within the meaning of Section 8-102(a)(9) of the UCC.

          (d)  In the event of any conflict between this Agreement (or any
portion thereof) and any other agreement now existing or hereafter entered into,
the terms of this Agreement shall prevail.

          (e)  The Purchase Contract Agent hereby irrevocably constitutes and
appoints the Collateral Agent and the Company, and each of them severally, with
full power of substitution, as the Purchase Contract Agent's attorney-in-fact to
take on behalf of, and in the name, place and stead of the Purchase Contract
Agent and the Holders, any action necessary or desirable to perfect and to keep
perfected the security interest in the Collateral referred to in Section 2.01.
The grant of such power-of-attorney shall not be deemed to require of the
Collateral Agent any specific duties or obligations not otherwise assumed by the
Collateral Agent hereunder.

          SECTION 2.03.  Termination.

          As to each Holder, this Agreement and the Pledge created hereby shall
terminate upon the satisfaction of such Holder's Obligations. Upon such
termination, the Collateral Agent shall instruct the Securities Intermediary to
Transfer such Holder's portion of the Collateral to the Purchase Contract Agent
for distribution to such Holder, free and clear of the Pledge created hereby.

                                        8

<PAGE>

                                   ARTICLE III

                       DISTRIBUTIONS ON PLEDGED COLLATERAL

          SECTION 3.01.  Income and Distributions.

          The Collateral Agent shall transfer all income and distributions
received by the Collateral Agent on account of the Pledged Subordinated Notes,
the Pledged Applicable Ownership Interests or Permitted Investments from time to
time held in the Collateral Account (_________________, Re: ONEOK, Inc.) to the
Purchase Contract Agent for distribution to the applicable Holders as provided
in the Purchase Contracts or Purchase Contract Agreement.

          SECTION 3.02.  Principal Payments Following Termination Event.

          Following a Termination Event, the Collateral Agent shall transfer all
principal payments it receives, if any, in respect of (a) the Pledged
Subordinated Notes, (b) the Pledged Applicable Ownership Interests, and (c) the
Pledged Treasury Securities, to the Purchase Contract Agent for the benefit of
the applicable Holders for distribution to such Holders in accordance with their
respective interests, free and clear of the Pledge created hereby.

          SECTION 3.03.  Principal Payments Prior to or on Purchase Contract
Settlement Date.

          (a)  Subject to the provisions of Section 4.06, and except as provided
in Section 3.03(b) below, if no Termination Event shall have occurred, all
principal payments received by the Securities Intermediary in respect of (i) the
Pledged Subordinated Notes, (ii) the Pledged Applicable Ownership Interests and
(iii) the Pledged Treasury Securities, shall be held and invested in Permitted
Investments until the Purchase Contract Settlement Date, and transferred to the
Company on the Purchase Contract Settlement Date as provided in Section 4.07
hereof. Any balance remaining in the Collateral Account shall be released from
the Pledge and transferred to the Purchase Contract Agent for the benefit of the
applicable Holders for distribution to such Holders in accordance with their
respective interests, free and clear of the Pledge created thereby. The Company
shall instruct the Collateral Agent in writing as to the type of Permitted
Investments in which any payments made under this Section 3.03(a) shall be
invested; provided, however, that if the Company fails to deliver such
instructions by 10:30 a.m. (New York City time) on the day such payments are
received by the Securities Intermediary, the Collateral Agent shall instruct the
Securities Intermediary to invest such payments in the Permitted Investments
described in clause (vi) of the definition of Permitted Investments. In no event
shall the Collateral Agent be liable for the selection of Permitted Investments
or for investment losses incurred thereon. The Collateral Agent shall have no
liability in respect of losses incurred as a result of the failure of the
Company to provide timely written investment direction.

          (b)  All principal payments received by the Securities Intermediary in
respect of (i) the Pledged Subordinated Notes, (ii) the Applicable Ownership
Interests (as specified in clause (i) of the definition thereof) in the Treasury
Portfolio and (iii) the Treasury Securities or security entitlements thereto,
that, in each case, have been released from the Pledge pursuant hereto shall

                                        9

<PAGE>

be transferred to the Purchase Contract Agent for the benefit of the applicable
Holders for distribution to such Holders in accordance with their respective
interests.

          SECTION 3.04.  Payments to Purchase Contract Agent.

          The Securities Intermediary shall use commercially reasonable efforts
to deliver payments to the Purchase Contract Agent hereunder to the account
designated by the Purchase Contract Agent for such purpose not later than 12:00
p.m. (New York City time) on the Business Day such payment is received by the
Securities Intermediary; provided, however, that if such payment is received on
a day that is not a Business Day or after 11:00 a.m. (New York City time) on a
Business Day, then the Securities Intermediary shall use commercially reasonable
efforts to deliver such payment to the Purchase Contract Agent no later than
10:30 a.m. (New York City time) on the next succeeding Business Day.

          SECTION 3.05.  Assets Not Properly Released.

          If the Purchase Contract Agent or any Holder shall receive any
principal payments on account of financial assets credited to the Collateral
Account and not released therefrom in accordance with this Agreement, the
Purchase Contract Agent or such Holder shall hold the same as trustee of an
express trust for the benefit of the Company and, upon receipt of an Officers'
Certificate of the Company so directing, promptly deliver the same to the
Securities Intermediary for credit to the Collateral Account or to the Company
for application to the Obligations of the Holders, and the Purchase Contract
Agent and Holders shall acquire no right, title or interest in any such payments
of principal amounts so received. The Purchase Contract Agent shall have no
liability under this Section 3.05 unless and until it has been notified in
writing that such payment was delivered to it erroneously and shall have no
liability for any action taken, suffered or omitted to be taken prior to its
receipt of such notice.

                                   ARTICLE IV

          INITIAL DEPOSIT; CREATION OF TREASURY UNITS AND RECREATION OF
                                 CORPORATE UNITS

          SECTION 4.01.  Initial Deposit of Subordinated Notes

          (a)  Prior to or concurrently with the execution and delivery of this
Agreement, the Purchase Contract Agent, on behalf of the initial Holders of the
Corporate Units, shall Transfer to the Securities Intermediary, for credit to
the Collateral Account, the Subordinated Notes or security entitlements relating
thereto, and, in the case of security entitlements, the Securities Intermediary
shall indicate by book-entry that a securities entitlement to such Subordinated
Notes has been credited to the Collateral Account.

          (b)  The Collateral Agent may, at any time or from time to time, in
its sole discretion, cause any or all securities or other property underlying
any financial assets credited to the Collateral Account to be registered in the
name of the Securities Intermediary, the Collateral Agent or their respective
nominees; provided, however, that unless any Event of Default (as defined in the
Indenture) shall have occurred and be continuing, the Collateral Agent agrees
not to cause any Subordinated Notes to be so re-registered.

                                       10

<PAGE>

          SECTION 4.02.  Creation of Treasury Units

          (a)  Unless the Treasury Portfolio has replaced the Subordinated Notes
as a component of the Corporate Units, a Holder of Corporate Units shall have
the right, at any time prior to 5:00 p.m. (New York City time) on the fifth
Business Day immediately preceding the Purchase Contract Settlement Date, to
create Treasury Units by substitution of Treasury Securities or security
entitlements with respect thereto for the Pledged Subordinated Notes comprising
a part of such Holder's Corporate Units, in integral multiples of ___ Corporate
Units by:

               (i)     Transferring to the Collateral Agent for credit to the
          Collateral Account Treasury Securities or security entitlements with
          respect thereto having a Value equal to the aggregate principal amount
          of the Pledged Subordinated Notes to be released, accompanied by a
          notice, substantially in the form of Exhibit C to the Purchase
          Contract Agreement, whereupon the Purchase Contract Agent shall
          deliver to the Collateral Agent a notice, substantially in the form of
          Exhibit A hereto, (A) stating that such Holder has notified the
          Purchase Contract Agent that such Holder has Transferred Treasury
          Securities or security entitlements with respect thereto to the
          Collateral Agent for credit to the Collateral Account, (B) stating the
          Value of the Treasury Securities or security entitlements with respect
          thereto Transferred by such Holder and (C) requesting that the
          Collateral Agent release from the Pledge the Pledged Subordinated
          Notes that are a component of such Corporate Units; and

               (ii)    delivering the related Corporate Units to the Purchase
          Contract Agent.

          Upon receipt of such notice and confirmation that Treasury Securities
or security entitlements with respect thereto have been credited to the
Collateral Account as described in such notice, the Collateral Agent shall
instruct the Securities Intermediary by a notice, substantially in the form of
Exhibit B, to release such Pledged Subordinated Notes from the Pledge by
Transfer to the Purchase Contract Agent for distribution to such Holder, free
and clear of the Pledge created hereby. If the Treasury Portfolio has replaced
the Subordinated Notes as a component of the Corporate Units and subject to the
conditions of the Purchase Contract Agreement, a Holder of Corporate Units may,
at any time on or prior to the second Business Day immediately preceding the
Purchase Contract Settlement Date, substitute Treasury Securities for the
Applicable Ownership Interests in the Treasury Portfolio with respect to such
Corporate Units, but only in multiples of __________ Corporate Units. In such an
event, the Holder shall transfer the required amount of Treasury Securities to
the Securities Intermediary, for credit to the Collateral Account, and the
Purchase Contract Agent shall request the Collateral Agent to instruct the
Securities Intermediary to release the Pledge of and transfer to the Holder the
appropriate Applicable Ownership Interests in the Treasury Portfolio in the
manner set forth above.

          (b)  Upon credit to the Collateral Account of Treasury Securities or
security entitlements with respect thereto delivered by a Holder of Corporate
Units and receipt of the related instruction from the Collateral Agent, the
Securities Intermediary shall release such Pledged Subordinated Notes or
Applicable Ownership Interest in the Treasury Portfolio, as the

                                       11

<PAGE>

case may be, and shall promptly Transfer the same to the Purchase Contract Agent
for distribution to such Holder, free and clear of the Pledge created hereby.

          SECTION 4.03.  Recreation of Corporate Units

          (a)  Unless the Treasury Portfolio has replaced the Subordinated Notes
as a component of the Corporate Units, at any time prior to 5:00 p.m. (New York
City time) on the fifth Business Day immediately preceding the Purchase Contract
Settlement Date, a Holder of Treasury Units shall have the right to recreate
Corporate Units by substitution of Subordinated Notes or security entitlements
with respect thereto for Pledged Treasury Securities in integral multiples of
___ Treasury Units by:

               (i)     Transferring to the Securities Intermediary for credit to
          the Collateral Account Subordinated Notes or security entitlements
          with respect thereto having a principal amount equal to the Value of
          the Pledged Treasury Securities to be released, accompanied by a
          notice, substantially in the form of Exhibit C to the Purchase
          Contract Agreement, whereupon the Purchase Contract Agent shall
          deliver to the Collateral Agent a notice, substantially in the form of
          Exhibit C hereto, stating that such Holder has Transferred the
          Subordinated Notes or security entitlements with respect thereto to
          the Collateral Account for credit to the Collateral Account and
          requesting that the Collateral Agent release from the Pledge the
          Pledged Treasury Securities related to such Treasury Units; and

               (ii)    delivering the related Treasury Units to the Purchase
          Contract Agent.

          Upon receipt of such notice and confirmation that Subordinated Notes
or security entitlements with respect thereto have been credited to the
Collateral Account as described in such notice, the Collateral Agent shall
instruct the Securities Intermediary by a notice substantially in the form of
Exhibit D hereto to release such Pledged Treasury Securities from the Pledge by
Transfer to the Purchase Contract Agent for distribution to such Holder, free
and clear of the Pledge created hereby.

          If the Treasury Portfolio has replaced the Subordinated Notes as a
component of the Corporate Units, a Holder of Treasury Units may, at any time on
or prior to the second Business Day immediately preceding the Purchase Contract
Settlement Date, substitute the Applicable Ownership Interests in the Treasury
Portfolio for the Pledged Treasury Securities with respect to such Treasury
Units, but only in multiples of ________ Treasury Units. In such an event, the
Holder shall Transfer the required Applicable Ownership Interests in the
Treasury Portfolio to the Securities Intermediary, for credit to the Collateral
Account, and the Purchase Contract Agent shall request the Collateral Agent to
instruct the Securities Intermediary to release and Transfer to the Holder the
Pledged Treasury Securities in the manner set forth above.

          (b)  Upon credit to the Collateral Account of Subordinated Notes or
security entitlements with respect thereto or Applicable Ownership Interests in
the Treasury Portfolio delivered by a Holder of Treasury Units and receipt of
the related instruction from the Collateral Agent, the Securities Intermediary
shall release such Pledged Treasury Securities and shall

                                       12

<PAGE>

promptly Transfer the same to the Purchase Contract Agent for distribution to
such Holder, free and clear of the Pledge created hereby.

          SECTION 4.04.  Termination Event

          (a)  Upon receipt by the Collateral Agent of written notice from the
Company or the Purchase Contract Agent that a Termination Event has occurred,
the Collateral Agent shall release all Collateral from the Pledge and shall
promptly instruct the Securities Intermediary to Transfer:

               (i)     any Pledged Subordinated Notes or security entitlements
          with respect thereto or Pledged Applicable Ownership Interests;

               (ii)    any Pledged Treasury Securities, and

               (iii)   any payments by Holders (or the Permitted Investments of
          such payments) pursuant to Section 4.05 hereof, to the Purchase
          Contract Agent for the benefit of the Holders for distribution to such
          Holders, in accordance with their respective interests, free and clear
          of the Pledge created hereby; provided, however, if any Holder shall
          be entitled to receive less than $__________ with respect to its
          interest in the Applicable Ownership Interests (as specified in clause
          (i) of the definition of such term) in the Treasury Portfolio, the
          Purchase Contract Agent shall have the right (but not the obligation)
          to dispose of such interest for cash and deliver to such Holder cash
          in lieu of delivering the Applicable Ownership Interests (as specified
          in clause (i) of the definition of such term) in the Treasury
          Portfolio.

          (b)  If such Termination Event shall result from the Company's
becoming a debtor under the Bankruptcy Code, and if the Collateral Agent shall
for any reason fail promptly to effectuate the release and Transfer of all
Pledged Subordinated Notes, Pledged Applicable Ownership Interests, Pledged
Treasury Securities and payments by Holders (or the Permitted Investments of
such payments) pursuant to Section 4.05 and Proceeds of any of the foregoing, as
the case may be, as provided by this Section 4.04, the Purchase Contract Agent
shall:

               (i)     use its best efforts to obtain an opinion of a nationally
          recognized law firm reasonably acceptable to the Collateral Agent to
          the effect that, notwithstanding the Company's being the debtor in
          such a bankruptcy case, the Collateral Agent will not be prohibited
          from releasing or Transferring the Collateral as provided in this
          Section 4.04, and shall deliver or cause to be delivered such opinion
          to the Collateral Agent within ten days after the occurrence of such
          Termination Event, and if (A) any Holder or the Purchase Contract
          Agent shall be unable to obtain such opinion within ten days after the
          occurrence of such Termination Event or (B) the Collateral Agent shall
          continue, after delivery of such opinion, to refuse to effectuate the
          release and Transfer of all Pledged Subordinated Notes, Pledged
          Applicable Ownership Interests, Pledged Treasury Securities and the
          payments by Holders (or the Permitted Investments of such payments)
          pursuant to Section 4.05 hereof and Proceeds of any of the foregoing,
          as the case may be, as provided in this Section 4.04, then any Holder
          may and the Purchase Contract Agent shall within fifteen days after
          the occurrence of such Termination Event commence an

                                       13

<PAGE>

          action or proceeding in the court having jurisdiction of the Company's
          case under the Bankruptcy Code seeking an order requiring the
          Collateral Agent to effectuate the release and transfer of all Pledged
          Subordinated Notes, Pledged Applicable Ownership Interests, Pledged
          Treasury Securities and the payments by Holders (or the Permitted
          Investments of such payments) pursuant to Section 4.05 hereof and
          Proceeds of any of the foregoing, or as the case may be, as provided
          by this Section 4.04; and

               (ii)    commence an action or proceeding like that described in
          Section 4.04(b)(i) hereof within ten days after the occurrence of such
          Termination Event.

          SECTION 4.05.  Cash Settlement

          (a)  Upon receipt by the Collateral Agent of (i) a notice from the
Purchase Contract Agent promptly after the receipt by the Purchase Contract
Agent of a notice from a Holder of Corporate Units or Treasury Units that such
Holder has elected, in accordance with the procedures specified in Section
5.02(b)(i) or (d)(i) of the Purchase Contract Agreement, respectively, to effect
a Cash Settlement and (ii) payment by such Holder by deposit in the Collateral
Account prior to 11:00 a.m. (New York City time) on the fourth Business Day
immediately preceding the Purchase Contract Settlement Date of the Purchase
Price in lawful money of the United States by certified or cashier's check or
wire transfer of immediately available funds payable to or upon the order of the
Securities Intermediary, then the Collateral Agent shall:

               (i)     instruct the Securities Intermediary promptly to invest
          any such Cash in Permitted Investments;

               (ii)    instruct the Securities Intermediary to release from the
          Pledge such Holder's related Pledged Subordinated Notes, Pledged
          Applicable Ownership Interests and Pledged Treasury Securities, as
          applicable, as to which such Holder has effected a Cash Settlement
          pursuant to this Section 4.05(a); and

               (iii)   instruct the Securities Intermediary to Transfer all such
          Pledged Subordinated Notes, Pledged Applicable Ownership Interests and
          the Pledged Treasury Securities, as the case may be, to the Purchase
          Contract Agent for distribution to such Holder, in each case free and
          clear of the Pledge created hereby.

          The Company shall instruct the Collateral Agent in writing as to the
type of Permitted Investments in which any such Cash shall be invested;
provided, however, that if the Company fails to deliver such written
instructions by 10:30 a.m. (New York City time) on the day such Cash is received
by the Collateral Agent or to be reinvested by the Securities Intermediary, the
Collateral Agent shall instruct the Securities Intermediary to invest such Cash
in the Permitted Investments described in clause (vi) of the definition of
Permitted Investments. In no event shall the Collateral Agent or Securities
Intermediary be liable for the selection of Permitted Investments or for
investment losses incurred thereon. The Collateral Agent and Securities
Intermediary shall have no liability in respect of losses incurred as a result
of the failure of the Company to provide timely written investment direction.

                                       14

<PAGE>

          Upon receipt of the proceeds upon the maturity of the Permitted
Investments on the Purchase Contract Settlement Date, the Collateral Agent shall
(A) instruct the Securities Intermediary to pay the portion of such proceeds and
deliver any certified or cashier's checks received, in an aggregate amount equal
to the Purchase Price, to the Company on the Purchase Contract Settlement Date,
and (B) release any amounts in excess of the Purchase Price earned from such
Permitted Investments to the Purchase Contract Agent for distribution to such
Holder.

          (b)  If a Holder of Corporate Units (unless the Treasury Portfolio has
replaced the Subordinated Notes as a component of such Corporate Units) (i)
fails to notify the Purchase Contract Agent of its intention to make a Cash
Settlement as provided in Section 5.02(b)(i) of the Purchase Contract Agreement
or (ii) does notify the Purchase Contract Agent of its intention to pay the
Purchase Price in cash, but fails to make such payment as required by Section
5.02(b)(ii) of the Purchase Contract Agreement, such Holder shall be deemed to
have consented to the disposition of such Holder's Pledged Subordinated Notes in
accordance with Section 5.02(b)(iii) of the Purchase Contract Agreement.

          (c)  If a Holder of a Treasury Unit or a Holder of a Corporate Unit
(if the Treasury Portfolio has replaced the Subordinated Notes as a component of
such Corporate Unit) (i) fails to notify the Purchase Contract Agent of its
intention to make a Cash Settlement as provided in Section 5.02(d)(i) of the
Purchase Contract Agreement or (ii) does notify the Purchase Contract Agent as
provided in Section 5.02(d)(ii) of the Purchase Contract Agreement of its
intention to pay the Purchase Price in cash, but fails to make such payment as
required by Section 5.02(d)(ii) of the Purchase Contract Agreement, such Holder
shall be deemed to have elected to pay the Purchase Price in accordance with
Section 5.02(d)(iii) of the Purchase Contract Agreement.

          (d)  As soon as practicable after 11:00 a.m. (New York City time) on
the fourth Business Day immediately preceding the Purchase Contract Settlement
Date, the Collateral Agent shall deliver to the Purchase Contract Agent a
notice, substantially in the form of Exhibit E hereto, stating (i) the amount of
Cash that it has received with respect to the Cash Settlement of Corporate
Units, (ii) the amount of Cash that it has received with respect to the Cash
Settlement of Treasury Units and (iii) the amount of Pledged Subordinated Notes
to be remarketed in the Final Remarketing pursuant to Section 5.02(c)(i) of the
Purchase Contract Agreement.

          (e)  If there has been a Failed Final Remarketing, as soon as
practicable after 11:00 a.m. (New York City time) on the Business Day
immediately preceding the Purchase Contract Settlement Date, the Collateral
Agent shall deliver to the Purchase Contract Agent a notice, stating (i) the
amount of Cash that it has received with respect to the Cash Settlement of
Corporate Units, (ii) the amount of Cash that it has received with respect to
the Cash Settlement of Treasury Units and (iii) the amount of Pledged
Subordinated Notes with respect to which an automatic deemed exercise of the Put
Right has occurred pursuant to Section 5.02(c)(iii) of the Purchase Contract
Agreement.

          SECTION 4.06.  Early Settlement and Cash Merger Early Settlement

          Upon receipt by the Collateral Agent of a notice from the Purchase
Contract Agent that a Holder of Units has elected to effect either (i) Early
Settlement of its obligations under the

                                       15

<PAGE>

Purchase Contracts forming a part of such Units in accordance with the terms of
the Purchase Contracts and Section 5.07 of the Purchase Contract Agreement or
(ii) Cash Merger Early Settlement of its obligations under the Purchase
Contracts forming a part of such Units in accordance with the terms of the
Purchase Contracts and Section 5.04(b)(ii) of the Purchase Contract Agreement
(which notice shall set forth the number of such Purchase Contracts as to which
such Holder has elected to effect Early Settlement or Cash Merger Early
Settlement), and that the Purchase Contract Agent has received from such Holder,
and paid to the Company as confirmed in writing by the Company, the related
Purchase Price pursuant to the terms of the Purchase Contracts and the Purchase
Contract Agreement and that all conditions to such Early Settlement or Cash
Merger Early Settlement, as the case may be, have been satisfied, then the
Collateral Agent shall release from the Pledge, (i) Pledged Subordinated Notes
or the Pledged Applicable Ownership Interests in the case of a Holder of
Corporate Units or (ii) Pledged Treasury Securities, in the case of a Holder of
Treasury Units, in each case with a Value equal to the product of (A) the Stated
Amount times (B) the number of Purchase Contracts as to which such Holder has
elected to effect Early Settlement or Cash Merger Early Settlement, and shall
instruct the Securities Intermediary to Transfer all such Pledged Applicable
Ownership Interests or Pledged Subordinated Notes or Pledged Treasury
Securities, as the case may be, to the Purchase Contract Agent for distribution
to such Holder, in each case free and clear of the Pledge created hereby. A
holder of Treasury Units may settle early only in integral multiples of ____
Treasury Units, and a Holder of Corporate Units, if the Treasury Portfolio has
replaced the Subordinated Notes as a component of such Corporate Units, may
settle early only in integral multiples of ________ Corporate Units.

          SECTION 4.07.  Application of Proceeds in Settlement of Purchase
Contracts

          (a)  If a Holder of Corporate Units (unless the Treasury Portfolio has
replaced the Subordinated Notes as a component of such Corporate Units) has not
elected to make an effective Cash Settlement by notifying the Purchase Contract
Agent in the manner provided for in Section 5.02(b)(i) of the Purchase Contract
Agreement or does notify the Purchase Contract Agent as provided in paragraph
5.02(b)(i) of the Purchase Contract Agreement of its intention to pay the
Purchase Price in cash, but fails to make such payment as required by paragraph
5.02(b)(ii) of the Purchase Contract Agreement, such Holder shall be deemed to
have elected to pay for the shares of Common Stock to be issued under such
Purchase Contracts from the Proceeds of the Final Remarketing of the related
Pledged Subordinated Notes. In the event of a Successful Final Remarketing, the
Collateral Agent shall instruct the Securities Intermediary to Transfer the
related Pledged Subordinated Notes to the Remarketing Agent, upon confirmation
of deposit by the Remarketing Agent of the Proceeds of such Final Remarketing
(less, to the extent permitted by the Remarketing Agreement, the Remarketing
Fee) in the Collateral Account. The Collateral Agent shall instruct the
Securities Intermediary to invest the Proceeds of the Final Remarketing in
Permitted Investments set forth in clause (vi) of the definition of Permitted
Investments. On the Purchase Contract Settlement Date, the Collateral Agent
shall, in consultation with the Purchase Contract Agent, instruct the Securities
Intermediary to remit a portion of the Proceeds from such Final Remarketing
equal to the aggregate principal amount of such Pledged Subordinated Notes to
satisfy in full such Holder's obligations to pay the Purchase Price to purchase
the shares of Common Stock under the related Purchase Contracts and to remit the
balance of the Proceeds from the Final Remarketing, if any, to the Purchase
Contract Agent for distribution to such Holder.

                                       16

<PAGE>

          Upon a Failed Final Remarketing, each Holder of Corporate Units
(unless the Treasury Portfolio has replaced the Subordinated Notes represented
by such Corporate Units) that has not elected to make an effective Cash
Settlement by notifying the Purchase Contract Agent in the manner provided for
in Section 5.02(e)(i) of the Purchase Contract Agreement or does notify the
Purchase Contract Agent as provided in paragraph 5.02(e)(i) of the Purchase
Contract Agreement of its intention to pay the Purchase Price in cash, but fails
to make such payment as required by paragraph 5.02(e)(ii) of the Purchase
Contract Agreement, shall be deemed to have exercised such Holder's Put Right
with respect to the Subordinated Notes that are a component of Corporate Units.
Upon exercise of the Put Right with respect to such Subordinated Notes, the
Company shall on the Purchase Contract Settlement Date cause the aggregate Put
Price with respect to such Subordinated Notes to be deposited in the Collateral
Account and the Collateral Agent shall cause the Securities Intermediary to
remit the Purchase Price for the shares of Common Stock to be issued under the
related Purchase Contract from a portion of the Proceeds of the Put Right to the
Company in full satisfaction of the Holder's obligations under the related
Purchase Contract; provided that if the Company shall fail to pay the Put Price
when due, the Company shall be deemed to have netted the Holders' obligations to
pay the aggregate Purchase Price under such Purchase Contracts against the
Company's obligation to pay the Put Price in full satisfaction of the Holders'
obligations under the Purchase Contracts. Following such payment or netting of
the Put Price, the Holders' obligations to pay the Purchase Price under the
Purchase Contracts will be deemed to be satisfied in full, and the Collateral
Agent shall cause the Securities Intermediary to release the Pledged
Subordinated Notes from the Collateral Account and shall promptly deliver the
Pledged Subordinated Notes to the Company. Thereafter, the Collateral Agent
shall promptly remit the remaining portion, if any, of the Put Price in excess
of the aggregate Purchase Price under such Purchase Contracts to the Purchase
Contract Agent for payment to the Holder of the Corporate Units to which such
Subordinated Notes relate.

          (b)  If a Holder of a Treasury Unit or a Holder of a Corporate Unit
(if the Treasury Portfolio has replaced the Subordinated Notes as a component of
such Corporate Unit) has not elected to make an effective Cash Settlement by
notifying the Purchase Contract Agent in the manner provided for in Section
5.02(d)(i) of the Purchase Contract Agreement, or has given such notice but
failed to make such payment in the manner required by Section 5.02(d)(ii) of the
Purchase Contract Agreement, such Holder shall be deemed to have elected to pay
for the shares of Common Stock to be issued under such Purchase Contracts from
the Proceeds of the related Pledged Treasury Securities or Pledged Applicable
Ownership Interests, as the case may be. Promptly, after 11:00 a.m. (New York
City time) on the Business Day immediately prior to the Purchase Contract
Settlement Date, the Collateral Agent shall invest the Cash Proceeds of the
maturing Pledged Treasury Securities or Pledged Applicable Ownership Interests,
as the case may be, in Permitted Investments set forth in clause (vi) of the
definition of Permitted Investments, unless prior to 10:30 a.m. (New York City
time) on such date, the Company shall otherwise instruct the Collateral Agent in
writing as to the type of Permitted Investments in which any such Cash Proceeds
shall be invested. In no event shall the Collateral Agent be liable for the
selection of Permitted Investments or for investment losses incurred thereon.
The Collateral Agent shall have no liability in respect of losses incurred as a
result of the failure of the Company to provide timely written investment
direction. Without receiving any instruction from any Holder, the Collateral
Agent shall instruct the Securities Intermediary to remit the Proceeds of the
related Pledged Treasury Securities or Pledged Applicable Ownership Interests,

                                       17

<PAGE>

as the case may be, to the settlement of such Purchase Contracts on the Purchase
Contract Settlement Date.

          In the event the sum of the Proceeds from the related Pledged Treasury
Securities or Pledged Applicable Ownership Interests, as the case may be, and
the investment earnings from the investment in Permitted Investments exceeds the
aggregate Purchase Price of the Purchase Contracts being settled thereby, the
Collateral Agent shall instruct the Securities Intermediary to transfer such
excess, when received, to the Purchase Contract Agent for distribution to
Holders.

          (c)  Prior to 5:00 p.m. (New York City time) on the fifth Business Day
immediately preceding the applicable Remarketing Date, but no earlier than the
Payment Date immediately preceding such date, Holders of Separate Subordinated
Notes may elect to have their Separate Subordinated Notes remarketed under the
Remarketing Agreement, by delivering their Separate Subordinated Notes along
with a notice of such election, substantially in the form of Exhibit F hereto,
to the Custodial Agent. After such time, such election shall become an
irrevocable election to have such Separate Subordinated Notes remarketed in such
Remarketing and, if such Remarketing fails, in any subsequent Remarketing. The
Custodial Agent shall hold Separate Subordinated Notes in an account separate
from the Collateral Account in which the Pledged Securities shall be held.
Holders of Separate Subordinated Notes electing to have their Separate
Subordinated Notes remarketed will also have the right to withdraw that election
by written notice to the Custodial Agent, substantially in the form of Exhibit G
hereto, prior to 5:00 p.m. (New York City time) on the fifth Business Day
immediately preceding the applicable Remarketing Date, upon which notice the
Custodial Agent shall return such Separate Subordinated Notes to such Holder.

          By 11:00 a.m. (New York City time) on the Business Day immediately
preceding the applicable Remarketing Date, the Custodial Agent shall notify the
Remarketing Agent of the aggregate principal amount of the Separate Subordinated
Notes to be remarketed and deliver to the Remarketing Agent for remarketing all
Separate Subordinated Notes delivered to the Custodial Agent pursuant to this
Section 4.07(c) and not validly withdrawn prior to such date. In the event of a
Successful Remarketing, after deducting the Remarketing Fee (to the extent
permitted under the terms of the Remarketing Agreement), the Remarketing Agent
will remit to the Custodial Agent the remaining portion of the Proceeds of such
Remarketing for payment to the Holders of the remarketed Separate Subordinated
Notes, in accordance with their respective interests. In the event of a Failed
Remarketing, the Remarketing Agent will promptly return such Separate
Subordinated Notes to the Custodial Agent, and, in the event of a Failed Final
Remarketing, the Custodial Agent shall deliver such Separate Subordinated Notes
to the appropriate Holders.

                                    ARTICLE V

                    VOTING RIGHTS PLEDGED SUBORDINATED NOTES

          SECTION 5.01.  Voting Rights

          Subject to the terms of Section 4.02 of the Purchase Contract
Agreement, the Purchase Contract Agent may exercise, or refrain from exercising,
any and all voting and other consensual

                                       18

<PAGE>

rights pertaining to the Pledged Subordinated Notes or any part thereof for any
purpose not inconsistent with the terms of this Agreement and in accordance with
the terms of the Purchase Contract Agreement; provided, that the Purchase
Contract Agent shall not exercise or, as the case may be, shall not refrain from
exercising such right if, in the judgment of the Purchase Contract Agent, such
action would impair or otherwise have a material adverse effect on the value of
all or any of the Pledged Subordinated Notes; and provided, further, that the
Purchase Contract Agent shall give the Company and the Collateral Agent at least
five Business Days' prior written notice of the manner in which it intends to
exercise, or its reasons for refraining from exercising, any such right. Upon
receipt of any notices and other communications in respect of any Pledged
Subordinated Notes, including notice of any meeting at which holders of the
Subordinated Notes are entitled to vote or solicitation of consents, waivers or
proxies of holders of the Subordinated Notes, the Collateral Agent shall use
reasonable efforts to send promptly to the Purchase Contract Agent such notice
or communication, and as soon as reasonably practicable after receipt of a
written request therefor from the Purchase Contract Agent, execute and deliver
to the Purchase Contract Agent such proxies and other instruments in respect of
such Pledged Subordinated Notes (in form and substance satisfactory to the
Collateral Agent) as are prepared by the Company and delivered to the Purchase
Contract Agent with respect to the Pledged Subordinated Notes.

                                   ARTICLE VI

                               RIGHTS AND REMEDIES

          SECTION 6.01.  Rights and Remedies of the Collateral Agent

          (a)  In addition to the rights and remedies specified in Section 4.07
hereof or otherwise available at law or in equity, after an event of default
hereunder, the Collateral Agent shall have all of the rights and remedies with
respect to the Collateral of a secured party under the UCC (whether or not the
UCC is in effect in the jurisdiction where the rights and remedies are asserted)
and the TRADES Regulations and such additional rights and remedies to which a
secured party is entitled under the laws in effect in any jurisdiction where any
rights and remedies hereunder may be asserted. Without limiting the generality
of the foregoing, such remedies may include, to the extent permitted by
applicable law, (i) retention of the Pledged Subordinated Notes, Pledged
Treasury Securities or the applicable Pledged Applicable Ownership Interests in
full satisfaction of the Holders' obligations under the Purchase Contracts and
the Purchase Contract Agreement or (ii) sale of the Pledged Subordinated Notes,
Pledged Treasury Securities or the applicable Pledged Applicable Ownership
Interests in one or more public or private sales and application of the proceeds
in full satisfaction of the Holders' obligations under the Purchase Contracts
and the Purchase Contract Agreement shall be deemed to have been satisfied in
full.

          (b)  Without limiting any rights or powers otherwise granted by this
Agreement to the Collateral Agent, in the event the Collateral Agent is unable
to make payments to the Company on account of the applicable Pledged Applicable
Ownership Interests, or on account of principal payments of any Pledged Treasury
Securities as provided in Article III hereof, in satisfaction of the Obligations
of the Holder of the Units of which such applicable Pledged Applicable Ownership
Interests or such Pledged Treasury Securities, as applicable, are a part under
the

                                       19

<PAGE>

related Purchase Contracts, the inability to make such payments shall constitute
an event of default hereunder and the Collateral Agent shall have and may
exercise, with reference to such Pledged Treasury Securities or Pledged
Applicable Ownership Interests, as applicable, and such obligations as such
Holder any and all of the rights and remedies available to a secured party under
the UCC and the TRADES Regulations after default by a debtor, and as otherwise
granted herein or under any other law.

          (c)  Without limiting any rights or powers otherwise granted by this
Agreement to the Collateral Agent, the Collateral Agent is hereby irrevocably
authorized to receive and collect all payments of (i) the principal amount of
the Pledged Subordinated Notes, (ii) the principal amount of the Pledged
Treasury Securities and (iii) the principal amount of the Pledged Applicable
Ownership Interests, subject, in each case, to the provisions of Article III
hereof, and as otherwise granted herein.

          (d)  The Purchase Contract Agent individually and as attorney-in-fact
for each Holder of Units in the event such Holder becomes the Holder of the
Treasury Units, agrees that, from time to time, upon the written request of the
Collateral Agent or the Purchase Contract Agent, such Holder shall execute and
deliver such further documents and do such other acts and things as the
Collateral Agent may reasonably request in order to maintain the Pledge, and the
perfection and priority thereof, and to confirm the rights of the Collateral
Agent hereunder. The Purchase Contract Agent shall have no liability to any
Holder for executing any documents or taking any such acts requested by the
Collateral Agent hereunder, except for liability for its own grossly negligent
acts, its own grossly negligent failure to act or its own willful misconduct.

          SECTION 6.02.  Special Event Redemption

          Upon the occurrence of a Special Event Redemption while Subordinated
Notes are still credited to the Collateral Account, the Collateral Agent is
hereby authorized to present the Pledged Subordinated Notes for payment as may
be required by their respective terms and to direct the Indenture Trustee to
remit the Redemption Price to the Securities Intermediary for credit to the
Collateral Account, on or prior to 12:30 p.m., New York City time on such
Special Event Redemption Date, by federal funds check or wire transfer of
immediately available funds. Upon receipt of such funds, the Pledged
Subordinated Notes shall be released from the Collateral Account and promptly
transferred to the Company. Upon the crediting of such funds to the Collateral
Account, the Collateral Agent, at the written direction of the Company, shall
instruct the Securities Intermediary to (a) apply an amount equal to the
Redemption Amount of such funds to purchase the Treasury Portfolio from the
Quotation Agent, (b) credit to the Collateral Account the Applicable Ownership
Interests specified in clause (i) of the definition of such term and (c)
promptly remit the remaining portion of such funds, if any, to the Purchase
Contract Agent for payment to the Holders of Corporate Units, in accordance with
their respective interests.

          SECTION 6.03.  Successful Initial Remarketing

          In the event of a Successful Remarketing prior to the Final
Remarketing Date, the Collateral Agent shall, at the direction of the Company,
instruct the Securities Intermediary to (a) Transfer the Pledged Subordinated
Notes to the Remarketing Agent upon confirmation of deposit

                                       20

<PAGE>

by the Remarketing Agent of the Proceeds of such Successful Remarketing (after
deducting any Remarketing Fee) in the Collateral Account, (b) apply an amount
equal to the Treasury Portfolio Purchase Price to purchase from the Quotation
Agent the Treasury Portfolio, (c) credit the Applicable Ownership Interests
specified in clause (i) of the definition of such term to the Collateral
Account, and (d) promptly remit the remaining portion of such Proceeds to the
Purchase Contract Agent for payment to the Holders of Corporate Units, in
accordance with their respective interests. With respect to Separate
Subordinated Notes, any Proceeds of such Remarketing (after deducting any
Remarketing Fee) attributable to the Separate Subordinated Notes will be
remitted to the Custodial Agent for payment to the holders of Separate
Subordinated Notes. The Pledged Applicable Ownership Interests thus credited to
the Collateral Account will secure the obligation of all Holders of Corporate
Units to purchase Common Stock of the Company under the Purchase Contracts
constituting a part of such Corporate Units, in substitution for the Pledged
Subordinated Notes, which shall be released from the Collateral Account. In the
event of a Failed Final Remarketing, the Pledged Subordinated Notes shall remain
credited to the Collateral Account and Section 4.07 shall apply.

          SECTION 6.04.  Substitutions

          Whenever a Holder has the right to substitute Treasury Securities,
Subordinated Notes or security entitlements for any of them or the appropriate
Applicable Ownership Interest (as defined in clause (i) of the definition of
such term) in the Treasury Portfolio, as the case may be, for financial assets
held in the Collateral Account, such substitution shall not constitute a
novation of the security interest created hereby.

                                   ARTICLE VII

                    REPRESENTATIONS AND WARRANTIES; COVENANTS

          SECTION 7.01.  Representations and Warranties

          Each Holder from time to time, acting through the Purchase Contract
Agent as attorney-in-fact (it being understood that the Purchase Contract Agent
shall not be liable for any representation or warranty made by or on behalf of a
Holder), hereby represents and warrants to the Collateral Agent (with respect to
such Holder's interest in the Collateral), which representations and warranties
shall be deemed repeated on each day a Holder Transfers Collateral, that:

          (a)  such Holder has the power to grant a security interest in and
lien on the Collateral;

          (b)  such Holder is the sole beneficial owner of the Collateral and,
in the case of Collateral delivered in physical form, is the sole holder of such
Collateral and is the sole beneficial owner of, or has the right to Transfer,
the Collateral it Transfers to the Collateral Agent for credit to the Collateral
Account, free and clear of any security interest, lien, encumbrance, call,
liability to pay money or other restriction other than the security interest and
lien granted under Article II hereof;

          (c)  upon the Transfer of the Collateral to the Collateral Agent for
credit to the Collateral Account, the Collateral Agent, for the benefit of the
Company, will have a valid and

                                       21

<PAGE>

perfected first priority security interest therein (assuming that any central
clearing operation or any securities intermediary or other entity not within the
control of the Holder involved in the Transfer of the Collateral, including the
Collateral Agent and the Securities Intermediary, gives the notices and takes
the action required of it hereunder and under applicable law for perfection of
that interest and assuming the establishment and exercise of control pursuant to
Section 2.02 hereof); and

          (d)  the execution and performance by the Holder of its obligations
under this Agreement will not result in the creation of any security interest,
lien or other encumbrance on the Collateral other than the security interest and
lien granted under Article II hereof or violate any provision of any existing
law or regulation applicable to it or of any mortgage, charge, pledge,
indenture, contract or undertaking to which it is a party or which is binding on
it or any of its assets.

          SECTION 7.02.  Covenants

          The Holders from time to time, acting through the Purchase Contract
Agent as their attorney-in-fact (it being understood that the Purchase Contract
Agent shall not be liable for any covenant made by or on behalf of a Holder),
hereby covenant to the Collateral Agent that for so long as the Collateral
remains subject to the Pledge:

          (a)  neither the Purchase Contract Agent nor such Holders will create
or purport to create or allow to subsist any mortgage, charge, lien, pledge or
any other security interest whatsoever over the Collateral or any part of it
other than pursuant to this Agreement; and

          (b)  neither the Purchase Contract Agent nor such Holders will sell or
otherwise dispose (or attempt to dispose) of the Collateral or any part of it
except for the beneficial interest therein, subject to the Pledge hereunder,
transferred in connection with the Transfer of the Units.

                                  ARTICLE VIII

          THE COLLATERAL AGENT, THE CUSTODIAL AGENT AND THE SECURITIES
                                  INTERMEDIARY

          It is hereby agreed as follows:

          SECTION 8.01.  Appointment, Powers and Immunities

          The Collateral Agent, the Custodial Agent or Securities Intermediary
shall act as agent for the Company hereunder with such powers as are
specifically vested in the Collateral Agent, the Custodial Agent or Securities
Intermediary, as the case may be, by the terms of this Agreement. Each of the
Collateral Agent, the Custodial Agent and Securities Intermediary shall:

          (a)  have no duties or responsibilities except those expressly set
forth in this Agreement and no implied covenants or obligations shall be
inferred from this Agreement against the Collateral Agent, the Custodial Agent
and Securities Intermediary, nor shall the Collateral Agent, the Custodial Agent
and Securities Intermediary be bound by the provisions of any agreement by any
party hereto beyond the specific terms hereof;

                                       22

<PAGE>

          (b)  not be responsible for any recitals contained in this Agreement,
or in any certificate or other document referred to or provided for in, or
received by it under, this Agreement, the Units or the Purchase Contract
Agreement, or for the value, validity, effectiveness, genuineness,
enforceability or sufficiency of this Agreement (other than as against the
Collateral Agent, the Custodial Agent or Securities Intermediary, as the case
may be), the Units, any Collateral or the Purchase Contract Agreement or any
other document referred to or provided for herein or therein or for any failure
by the Company or any other Person (except the Collateral Agent, the Custodial
Agent or Securities Intermediary, as the case may be) to perform any of its
obligations hereunder or thereunder or for the perfection, priority or, except
as expressly required hereby, maintenance of any security interest created
hereunder;

          (c)  not be required to initiate or conduct any litigation or
collection proceedings hereunder (except pursuant to directions furnished under
Section 8.02 hereof, subject to Section 8.08 hereof);

          (d)  not be responsible for any action taken or omitted to be taken by
it hereunder or under any other document or instrument referred to or provided
for herein or in connection herewith or therewith, except for its own gross
negligence, bad faith or willful misconduct;

          (e)  not be required to advise any party as to selling or retaining,
or taking or refraining from taking any action with respect to, any securities
or other property deposited hereunder; and

          (f)  not be responsible to make or give any presentments, demands for
performance, notices of nonperformance, protests, notices of protest, or notice
of dishonor in connection with any obligation of evidences of indebtedness held
thereunder as Collateral.

          Subject to the foregoing, during the term of this Agreement, the
Collateral Agent, the Custodial Agent and the Securities Intermediary shall take
all reasonable action in connection with the safekeeping and preservation of the
Collateral hereunder as determined by industry standards.

          No provision of this Agreement shall require the Collateral Agent,
Custodial Agent or Securities Intermediary to expend or risk its own funds or
otherwise incur any financial liability in the performance of any of its duties
hereunder. In no event shall the Collateral Agent, Custodial Agent or Securities
Intermediary be liable for any amount in excess of the Value of the Collateral.
Notwithstanding the foregoing, the Collateral Agent, the Custodial Agent and the
Securities Intermediary, each in its own individual capacity, hereby waive any
right of setoff, bankers liens, liens or perfection rights as Securities
Intermediary or any counterclaim with respect to any of the Collateral.

          SECTION 8.02.  Instructions of the Company

          The Company shall have the right, by one or more instruments in
writing executed and delivered to the Collateral Agent, the Custodial Agent or
the Securities Intermediary, as the case may be, to direct the time, method and
place of conducting any proceeding for the realization of any right or remedy
available to the Collateral Agent, or of exercising any power conferred on the
Collateral Agent, the Custodial Agent or the Securities Intermediary, as the
case may be, or

                                       23

<PAGE>

to direct the taking or refraining from taking of any action authorized by this
Agreement; provided, however, that (a) such direction shall not conflict with
the provisions of any law or of this Agreement or involve the Collateral Agent
in personal liability and (b) the Collateral Agent, the Custodial Agent or the
Securities Intermediary, as the case may be, shall be indemnified to its
satisfaction as provided herein. Nothing contained in this Section 8.02 shall
impair the right of the Collateral Agent in its discretion to take any action or
omit to take any action which it deems proper and which is not inconsistent with
such direction.

          SECTION 8.03.  Reliance by Collateral Agent and Securities
Intermediary

          Each of the Securities Intermediary, the Custodial Agent and the
Collateral Agent shall be entitled conclusively to rely upon any certification,
order, judgment, opinion, notice or other written communication (including,
without limitation, any thereof by e-mail or similar electronic means, telecopy,
telex or facsimile) reasonably believed by it to be genuine and correct and to
have been signed or sent by or on behalf of the proper Person or Persons
(without being required to determine the correctness of any fact stated therein)
and consult with and conclusively rely upon advice, opinions and statements of
legal counsel and other experts selected by the Collateral Agent, the Custodial
Agent or the Securities Intermediary, as the case may be. As to any matters not
expressly provided for by this Agreement, the Collateral Agent, the Custodial
Agent and the Securities Intermediary shall in all cases be fully protected in
acting, or in refraining from acting, hereunder in accordance with instructions
given by the Company in accordance with this Agreement.

          SECTION 8.04.  Certain Rights

          (a)  Whenever in the administration of the provisions of this
Agreement the Collateral Agent, the Custodial Agent or the Securities
Intermediary shall deem it necessary or desirable that a matter be proved or
established prior to taking or suffering any action to be taken hereunder, such
matter (unless other evidence in respect thereof be herein specifically
prescribed) may, in the absence of gross negligence, bad faith or willful
misconduct on the part of the Collateral Agent, the Custodial Agent or the
Securities Intermediary, be deemed to be conclusively proved and established by
a certificate signed by one of the Company's officers, and delivered to the
Collateral Agent, the Custodial Agent or the Securities Intermediary and such
certificate, in the absence of gross negligence, bad faith or willful misconduct
on the part of the Collateral Agent, the Custodial Agent or the Securities
Intermediary, shall be full warrant to the Collateral Agent, the Custodial Agent
or the Securities Intermediary for any action taken, suffered or omitted by it
under the provisions of this Agreement upon the faith thereof.

          (b)  The Collateral Agent, the Custodial Agent or the Securities
Intermediary shall not be bound to make any investigation into the facts or
matters stated in any resolution, certificate, statement, instrument, opinion,
report, notice, request, consent, entitlement order, approval or other paper or
document.

          SECTION 8.05.  Merger, Conversion, Consolidation or Succession to
Business

          Any corporation into which the Collateral Agent, the Custodial Agent
or the Securities Intermediary may be merged or converted or with which it may
be consolidated, or any

                                       24

<PAGE>

corporation resulting from any merger, conversion or consolidation to which the
Collateral Agent, the Custodial Agent or the Securities Intermediary shall be a
party, or any corporation succeeding to the business of the Collateral Agent,
the Custodial Agent or the Securities Intermediary shall be the successor of the
Collateral Agent, the Custodial Agent or the Securities Intermediary hereunder
without the execution or filing of any paper with any party hereto or any
further act on the part of any of the parties hereto except where an instrument
of transfer or assignment is required by law to effect such succession, anything
herein to the contrary notwithstanding.

          SECTION 8.06.  Rights in Other Capacities

          The Collateral Agent, the Custodial Agent and the Securities
Intermediary and their affiliates may (without having to account therefor to the
Company) accept deposits from, lend money to, make their investments in and
generally engage in any kind of banking, trust or other business with the
Purchase Contract Agent, any other Person interested herein and any Holder of
Units (and any of their respective subsidiaries or affiliates) as if it were not
acting as the Collateral Agent, the Custodial Agent or the Securities
Intermediary, as the case may be, and the Collateral Agent, the Custodial Agent,
the Securities Intermediary and their affiliates may accept fees and other
consideration from the Purchase Contract Agent and any Holder of Units without
having to account for the same to the Company; provided that each of the
Securities Intermediary, the Custodial Agent and the Collateral Agent covenants
and agrees with the Company that it shall not accept, receive or permit there to
be created in favor of itself and shall take no affirmative action to permit
there to be created in favor of any other Person, any security interest, lien or
other encumbrance of any kind in or upon the Collateral other than the lien
created by the Pledge and the Collateral shall be segregated on the books and
records of the Collateral Agent and not commingled with any other assets of such
Person.

          SECTION 8.07.  Non-reliance on Collateral Agent, the Custodial Agent
and Securities Intermediary

          None of the Securities Intermediary, the Custodial Agent or the
Collateral Agent shall be required to keep itself informed as to the performance
or observance by the Purchase Contract Agent or any Holder of Units of this
Agreement, the Purchase Contract Agreement, the Units or any other document
referred to or provided for herein or therein or to inspect the properties or
books of the Purchase Contract Agent or any Holder of Units. None of the
Collateral Agent, the Custodial Agent or the Securities Intermediary shall have
any duty or responsibility to provide the Company with any credit or other
information concerning the affairs, financial condition or business of the
Purchase Contract Agent or any Holder of Units (or any of their respective
affiliates) that may come into the possession of the Collateral Agent, the
Custodial Agent or the Securities Intermediary or any of their respective
affiliates.

          SECTION 8.08.  Compensation and Indemnity

          The Company agrees to:

          (a)  pay the Collateral Agent, the Custodial Agent and the Securities
Intermediary from time to time such compensation as shall be agreed in writing
between the Company and the

                                       25

<PAGE>

Collateral Agent, the Custodial Agent or the Securities Intermediary, as the
case may be, for all services rendered by them hereunder;

          (b)  indemnify, defend and hold harmless the Collateral Agent, the
Custodial Agent, the Securities Intermediary and each of their respective
directors, officers, agents and employees (collectively, the "Indemnitees"),
harmless from and against any and all claims, liabilities, losses, damages,
fines, penalties and expenses (including reasonable fees and expenses of
counsel) (collectively, "Losses" and individually, a "Loss") that may be imposed
on, reasonably incurred by, or asserted against, the Indemnitees or any of them
for following any instructions or other directions upon which any of the
Indemnitees is entitled to rely pursuant to the terms of this Agreement,
provided that such Indemnitee has not acted with gross negligence or bad faith
or engaged in willful misconduct with respect to the specific Loss against which
indemnification is sought; and

          (c)  in addition to and not in limitation of paragraph (b) immediately
above, indemnify and hold the Indemnitees and each of them harmless from and
against any and all Losses that may be imposed on, incurred by or asserted
against, the Indemnitees or any of them in connection with or arising out of the
Collateral Agent's, the Custodial Agent's or the Securities Intermediary's
acceptance, performance or exercise of its rights, powers and duties under this
Agreement, provided the Collateral Agent, the Custodial Agent or the Securities
Intermediary, as the case may be, has not acted with gross negligence or bad
faith or engaged in willful misconduct with respect to the specific Loss against
which indemnification is sought.

          The provisions of this Section and Section 10.07 shall survive the
resignation or removal of the Collateral Agent, Custodial Agent or Securities
Intermediary and the termination of this Agreement.

          SECTION 8.09.  Failure to Act

          In the event of any ambiguity in the provisions of this Agreement or
any dispute between or conflicting claims by or among the parties hereto or any
other Person with respect to any funds or property deposited hereunder, then at
its sole option, each of the Collateral Agent, the Custodial Agent and the
Securities Intermediary shall be entitled, after prompt notice to the Company
and the Purchase Contract Agent, to refuse to comply with any and all claims,
demands or instructions with respect to such property or funds so long as such
dispute or conflict shall continue, and the Collateral Agent, the Custodial
Agent and the Securities Intermediary shall not be or become liable in any way
to any of the parties hereto for its failure or refusal to comply with such
conflicting claims, demands or instructions. The Collateral Agent, the Custodial
Agent and the Securities Intermediary shall be entitled to refuse to act until
either:

          (a)  such conflicting or adverse claims or demands shall have been
finally determined by a court of competent jurisdiction or settled by agreement
between the conflicting parties as evidenced in a writing satisfactory to the
Collateral Agent, the Custodial Agent or the Securities Intermediary, as the
case may be, or

          (b)  the Collateral Agent, the Custodial Agent or the Securities
Intermediary, as the case may be, shall have received security or an indemnity
satisfactory to it sufficient to save it

                                       26

<PAGE>

harmless from and against any and all loss, liability or reasonable
out-of-pocket expense which it may incur by reason of its acting at the expense
of the Company.

          The Collateral Agent, the Custodial Agent and the Securities
Intermediary may in addition elect to commence an interpleader action or seek
other judicial relief or orders as the Collateral Agent, the Custodial Agent or
the Securities Intermediary may deem necessary. Notwithstanding anything
contained herein to the contrary, none of the Collateral Agent, the Custodial
Agent or the Securities Intermediary shall be required to take any action that
is in its opinion contrary to law or to the terms of this Agreement, or which
would in its opinion subject it or any of its officers, employees or directors
to liability.

          SECTION 8.10.  Resignation of Collateral Agent, the Custodial Agent
and Securities Intermediary

          Subject to the appointment and acceptance of a successor Collateral
Agent, Custodial Agent or Securities Intermediary as provided below:

          (a)  the Collateral Agent, the Custodial Agent and the Securities
Intermediary may resign at any time by giving notice thereof to the Company and
the Purchase Contract Agent as attorney-in-fact for the Holders of Units;

          (b)  the Collateral Agent, the Custodial Agent and the Securities
Intermediary may be removed at any time by the Company; and

          (c)  if the Collateral Agent, the Custodial Agent or the Securities
Intermediary fails to perform any of its material obligations hereunder in any
material respect for a period of not less than 20 days after receiving written
notice of such failure by the Purchase Contract Agent and such failure shall be
continuing, the Collateral Agent, the Custodial Agent and the Securities
Intermediary may be removed by the Purchase Contract Agent, acting at the
direction of the Holders of a majority of the Units.

          The Purchase Contract Agent shall promptly notify the Company of any
removal of the Collateral Agent, the Custodial Agent or the Securities
Intermediary pursuant to clause (c) of this Section 8.10. Upon any such
resignation or removal, the Company shall have the right to appoint a successor
Collateral Agent, Custodial Agent or Securities Intermediary, as the case may
be, which shall not be an Affiliate of the Purchase Contract Agent. If no
successor Collateral Agent, Custodial Agent or Securities Intermediary, as the
case may be, shall have been so appointed and shall have accepted such
appointment within 30 days after the retiring Collateral Agent's, Custodial
Agent's or Securities Intermediary's giving of notice of resignation or the
Company's or the Purchase Contract Agent's giving notice of such removal, then
the retiring or removed Collateral Agent, Custodial Agent or Securities
Intermediary may petition any court of competent jurisdiction, at the expense of
the Company, for the appointment of a successor Collateral Agent, Custodial
Agent or Securities Intermediary, as the case may be. The Collateral Agent, the
Custodial Agent and the Securities Intermediary shall each be a bank or a
national banking association which has an office (or an agency office) in New
York City with a combined capital and surplus of at least $50,000,000. Upon the
acceptance of any appointment as Collateral Agent, Custodial Agent or Securities
Intermediary hereunder, as the case may be,

                                       27

<PAGE>

by a successor Collateral Agent, Custodial Agent or Securities Intermediary, as
the case may be, such successor Collateral Agent, Custodial Agent or Securities
Intermediary, as the case may be, shall thereupon succeed to and become vested
with all the rights, powers, privileges and duties of the retiring Collateral
Agent, Custodial Agent or Securities Intermediary, as the case may be, and the
retiring Collateral Agent, Custodial Agent or Securities Intermediary, as the
case may be, shall take all appropriate action, subject to payment of any
amounts then due and payable to it hereunder, to transfer any money and property
held by it hereunder (including the Collateral) to such successor. The retiring
Collateral Agent, Custodial Agent or Securities Intermediary shall, upon such
succession, be discharged from its duties and obligations as Collateral Agent,
Custodial Agent or Securities Intermediary hereunder. After any retiring
Collateral Agent's, Custodial Agent's or Securities Intermediary's resignation
hereunder as Collateral Agent, Custodial Agent or Securities Intermediary, the
provisions of this Article VIII shall continue in effect for its benefit in
respect of any actions taken or omitted to be taken by it while it was acting as
the Collateral Agent, Custodial Agent or Securities Intermediary. Any
resignation or removal of the Collateral Agent, Custodial Agent or Securities
Intermediary hereunder, at a time when such Person is acting as the Collateral
Agent, Custodial Agent or Securities Intermediary, shall be deemed for all
purposes of this Agreement as the simultaneous resignation or removal of the
Collateral Agent, Securities Intermediary or Custodial Agent, as the case may
be.

          (d)  [To be used if SunTrust Bank is the Collateral Agent] Since
SunTrust Bank is serving as the Collateral Agent hereunder and the Purchase
Contract Agent under the Purchase Contract Agreement, if an event of default
(other than an event of default occurring as a result of a Failed Final
Remarketing) occurs hereunder or under the Purchase Contract Agreement, SunTrust
Bank will resign as the Collateral Agent, but continue to act as the Purchase
Contract Agent. A successor Collateral Agent will be appointed in accordance
with the terms hereof.

          SECTION 8.11.  Right to Appoint Agent or Advisor

          The Collateral Agent shall have the right to appoint agents or
advisors in connection with any of its duties hereunder, and the Collateral
Agent shall not be liable for any action taken or omitted by, or in reliance
upon the advice of, such agents or advisors selected in good faith. The
appointment of agents pursuant to this Section 8.11 shall be subject to prior
written consent of the Company, which consent shall not be unreasonably
withheld.

          SECTION 8.12.  Survival

          The provisions of this Article VIII shall survive termination of this
Agreement and the resignation or removal of the Collateral Agent, the Custodial
Agent or the Securities Intermediary.

          SECTION 8.13.  Exculpation

          Anything contained in this Agreement to the contrary notwithstanding,
in no event shall the Collateral Agent, the Custodial Agent or the Securities
Intermediary or their officers, directors, employees or agents be liable under
this Agreement to the Company or any third party for indirect, special,
punitive, or consequential loss or damage of any kind whatsoever, including, but
not limited to, lost profits, whether or not the likelihood of such loss or
damage was known

                                       28

<PAGE>

to the Collateral Agent, the Custodial Agent or the Securities Intermediary, or
any of them and regardless of the form of action.

                                   ARTICLE IX

                                    AMENDMENT

          SECTION 9.01.  Amendment Without Consent of Holders

          Without the consent of any Holders, the Company, when authorized by a
Board Resolution, the Collateral Agent, the Custodial Agent, the Securities
Intermediary and the Purchase Contract Agent, at any time and from time to time,
may amend this Agreement, in form satisfactory to the Company, the Collateral
Agent, the Custodial Agent, the Securities Intermediary and the Purchase
Contract Agent, to:

          (a)  evidence the succession of another Person to the Company and the
assumption by any such successor of the covenants of the Company;

          (b)  evidence and provide for the acceptance of appointment hereunder
by a successor Collateral Agent, Custodial Agent, Securities Intermediary or
Purchase Contract Agent;

          (c)  add to the covenants of the Company for the benefit of the
Holders, or surrender any right or power herein conferred upon the Company,
provided that such covenants or such surrender do not adversely affect the
validity, perfection or priority of the security interests granted or created
hereunder; or

          (d)  cure any ambiguity (or formal defect), correct or supplement any
provisions herein which may be inconsistent with any other such provisions
herein, or make any other provisions with respect to such matters or questions
arising under this Agreement, provided that such action shall not adversely
affect the interests of the Holders in any material respect.

          SECTION 9.02.  Amendment with Consent of Holders

          With the consent of the Holders of not less than a majority of the
Purchase Contracts at the time outstanding, including, without limitation, the
consent of the Holders obtained in connection with a tender or an exchange
offer, by Act of such Holders delivered to the Company, the Purchase Contract
Agent, the Custodial Agent, the Securities Intermediary and the Collateral
Agent, as the case may be, the Company, when duly authorized by a Board
Resolution, the Purchase Contract Agent, the Collateral Agent, the Securities
Intermediary and the Collateral Agent may amend this Agreement for the purpose
of modifying in any manner the provisions of this Agreement or the rights of the
Holders in respect of the Units; provided, however, that no such supplemental
agreement shall, without the unanimous consent of the Holders of each
Outstanding Unit adversely affected thereby in any material respect:

          (a)  change the amount or type of Collateral underlying a Unit (except
for the rights of holders of Corporate Units to substitute the Treasury
Securities for the Pledged Subordinated Notes or the Pledged Applicable
Ownership Interests, as the case may be, or the rights of Holders of Treasury
Units to substitute Subordinated Notes or the Applicable Ownership

                                       29

<PAGE>

Interests (as specified in clause (i) of the definition of such term) in the
Treasury Portfolio, as applicable, for the Pledged Treasury Securities), unless
such change is not adverse to the Holders, impair the right of the Holder of any
Unit to receive distributions on the underlying Collateral or otherwise
adversely affect the Holder's rights in or to such Collateral; or

          (b)  otherwise effect any action that would require the consent of the
Holder of each Outstanding Unit affected thereby pursuant to the Purchase
Contract Agreement if such action were effected by a modification or amendment
of the provisions of the Purchase Contract Agreement; or

          (c)  reduce the percentage of Purchase Contracts the consent of whose
Holders is required for any such amendment;

          provided that if any amendment or proposal referred to above would
adversely affect only the Corporate Units or only the Treasury 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 the
Holders of not less than a majority of such class; 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 (a) through (c) above. It shall not be necessary for any
Act of Holders under this Section to approve the particular form of any proposed
amendment, but it shall be sufficient if such Act shall approve the substance
thereof.

          SECTION 9.03.  Execution of Amendments

          In executing any amendment permitted by this Article, the Collateral
Agent, the Custodial Agent, the Securities Intermediary and the Purchase
Contract Agent shall be entitled to receive and (subject to Section 6.01 hereof,
with respect to the Collateral Agent, and Section 7.01 of the Purchase Contract
Agreement with respect to the Purchase Contract Agent) shall be fully authorized
and protected in relying upon, an Opinion of Counsel stating that the execution
of such amendment is authorized or permitted by this Agreement and that all
conditions precedent, if any, to the execution and delivery of such amendment
have been satisfied. The Collateral Agent, Custodial Agent, Securities
Intermediary and Purchase Contract Agent may, but shall not be obligated to,
enter into any such amendment which affects their own respective rights, duties
or immunities under this Agreement or otherwise. All amendments must be in
writing, signed by all parties to this Agreement.

          SECTION 9.04.  Effect of Amendments

          Upon the execution of any amendment under this Article, this Agreement
shall be modified in accordance therewith, and such amendment 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
under the Purchase Contract Agreement shall be bound thereby.

                                       30

<PAGE>

          SECTION 9.05.  Reference of Amendments

          Certificates authenticated, executed on behalf of the Holders and
delivered after the execution of any amendment pursuant to this Section may, and
shall if required by the Collateral Agent or the Purchase Contract Agent, bear a
notation in form approved by the Purchase Contract Agent and the Collateral
Agent as to any matter provided for in such amendment. If the Company shall so
determine, new Certificates so modified as to conform, in the opinion of the
Collateral Agent, the Purchase Contract Agent and the Company, to any such
amendment may be prepared and executed by the Company and authenticated,
executed on behalf of the Holders and delivered by the Purchase Contract Agent
in accordance with the Purchase Contract Agreement in exchange for Certificates
representing Outstanding Units.

                                    ARTICLE X

                                  MISCELLANEOUS

          SECTION 10.01. No Waiver

          To the extent permitted by law, no failure on the part of the Company,
the Collateral Agent, the Custodial Agent, the Securities Intermediary or any of
their respective agents to exercise, and no course of dealing with respect to,
and no delay in exercising, any right, power or remedy hereunder shall operate
as a waiver thereof; nor shall any single or partial exercise by the Company,
the Collateral Agent, the Custodial Agent, the Securities Intermediary or any of
their respective agents of any right, power or remedy hereunder preclude any
other or further exercise thereof or the exercise of any other right, power or
remedy. The remedies herein are cumulative and are not exclusive of any remedies
provided by law.

          SECTION 10.02. Governing Law; Submission to Jurisdiction

          THIS AGREEMENT SHALL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH,
THE LAWS OF THE STATE OF NEW YORK WITHOUT GIVING EFFECT TO THE CONFLICTS OF LAW
PROVISIONS THEREOF. Without limiting the foregoing, the above choice of law is
expressly agreed to by the Company, the Securities Intermediary, the Custodial
Agent, the Collateral Agent and the Holders from time to time acting through the
Purchase Contract Agent, as their attorney in fact, in connection with the
establishment and maintenance of the Collateral Account. The Company, the
Collateral Agent, the Custodial Agent, the Securities Intermediary and the
Holders from time to time of the Units, acting through the Purchase Contract
Agent as their attorney-in-fact, hereby submit to the nonexclusive jurisdiction
of the United States District Court for the Southern District of New York and of
any New York state court sitting in New York City for the purposes of all legal
proceedings arising out of or relating to this Agreement or the transactions
contemplated hereby. The Company, the Collateral Agent, the Custodial Agent, the
Securities Intermediary and the Holders from time to time of the Units, acting
through the Purchase Contract Agent as their attorney-in-fact, irrevocably
waive, to the fullest extent permitted by applicable law, any objection which
they may now or hereafter have to the laying of the venue of any such proceeding
brought in such a court and any claim that any such proceeding brought in such a
court has been brought in an inconvenient forum.

                                       31

<PAGE>

          SECTION 10.03. Notices

          All notices, requests, consents and other communications provided for
herein (including, without limitation, any modifications of, or waivers or
consents under, this Agreement) shall be given or made in writing (including,
without limitation, by telecopy) delivered to the intended recipient at the
"Address for Notices" specified below its name on the signature pages hereof (or
in the case of Holders, may be made and deemed given as provided in Section 1.05
and 1.06 of the Purchase Contract Agreement) or, as to any party, at such other
address as shall be designated by such party in a notice to the other parties.
Except as otherwise provided in this Agreement, all such communications shall be
deemed to have been duly given when transmitted by telecopier or personally
delivered or, in the case of a mailed notice, upon receipt, in each case given
or addressed as aforesaid (except as aforesaid).

          SECTION 10.04. Successors and Assigns

          This Agreement shall be binding upon and inure to the benefit of the
respective successors and assigns of the Company, the Collateral Agent, the
Custodial Agent, the Securities Intermediary and the Purchase Contract Agent,
and the Holders from time to time of the Units, by their acceptance of the same,
shall be deemed to have agreed to be bound by the provisions hereof and to have
ratified the agreements of, and the grant of the Pledge hereunder by, the
Purchase Contract Agent.

          SECTION 10.05. Counterparts

          This Agreement may be executed in any number of counterparts, all of
which taken together shall constitute one and the same instrument, and any of
the parties hereto may execute this Agreement by signing any such counterpart.

          SECTION 10.06. Severability

          If any provision hereof is invalid and unenforceable in any
jurisdiction, then, to the fullest extent permitted by law, (i) the other
provisions hereof shall remain in full force and effect in such jurisdiction and
shall be liberally construed in order to carry out the intentions of the parties
hereto as nearly as may be possible and (ii) the invalidity or unenforceability
of any provision hereof in any jurisdiction shall not affect the validity or
enforceability of such provision in any other jurisdiction.

          SECTION 10.07. EXPENSES, ETC.

          The Company agrees to reimburse the Collateral Agent, the Custodial
Agent and the Securities Intermediary for: (a) all reasonable costs and expenses
of the Collateral Agent, the Custodial Agent and the Securities Intermediary
(including, without limitation, the reasonable fees and expenses of counsel to
the Collateral Agent, the Custodial Agent and the Securities Intermediary),
reasonably incurred in connection with (i) the negotiation, preparation,
execution and delivery or performance of this Agreement and (ii) any
modification, supplement or waiver of any of the terms of this Agreement; (b)
all reasonable costs and expenses of the Collateral Agent, the Custodial Agent
and the Securities Intermediary (including, without limitation, reasonable fees
and expenses of counsel) reasonably incurred in connection with (i) any
enforcement or proceedings resulting or incurred in connection with causing any
Holder of Units to satisfy its obligations under the Purchase Contracts forming
a part of the Units and (ii) the

                                       32

<PAGE>

enforcement of this Section 10.7; and (c) all transfer, stamp, documentary or
other similar taxes, assessments or charges levied by any governmental or
revenue authority in respect of this Agreement or any other document referred to
herein and all costs, expenses, taxes, assessments and other charges reasonably
incurred in connection with any filing, registration, recording or perfection of
any security interest contemplated hereby; (d) all reasonable fees and expenses
of any agent or advisor appointed by the Collateral Agent and consented to by
the Company under Section 8.11 of this Agreement, (e) any out-of-pocket costs
and expenses reasonably incurred by the Collateral Agent, the Custodial Agent,
and the Securities Intermediary in connection with the exercise of their rights
or performance of their obligations and duties under Section 8.10 hereof; and
(f) any other reasonable out-of-pocket costs and expenses reasonably incurred by
the Collateral Agent, the Custodial Agent and the Securities Intermediary in
connection with the performance of their duties hereunder.

          SECTION 10.08. Security Interest Absolute

          All rights of the Collateral Agent and security interests hereunder,
and all obligations of the Holders from time to time hereunder, shall be
absolute and unconditional irrespective of:

          (a)  any lack of validity or enforceability of any provision of the
Purchase Contracts or the Units or any other agreement or instrument relating
thereto;

          (b)  any change in the time, manner or place of payment of, or any
other term of, or any increase in the amount of, all or any of the obligations
of Holders of the Units under the related Purchase Contracts, or any other
amendment or waiver of any term of, or any consent to any departure from any
requirement of, the Purchase Contract Agreement or any Purchase Contract or any
other agreement or instrument relating thereto; or

          (c)  any other circumstance which might otherwise constitute a defense
available to, or discharge of, a borrower, a guarantor or a pledgor.

          SECTION 10.09. Notice of Special Event, Special Event Redemption and
Termination Event

          Upon the occurrence of a Special Event, a Special Event Redemption or
a Termination Event, the Company shall deliver written notice to the Purchase
Contract Agent, the Collateral Agent and the Securities Intermediary. Upon the
written request of the Collateral Agent or the Securities Intermediary, the
Company shall inform such party whether or not a Special Event, a Special Event
Redemption or a Termination Event has occurred.

                       [SIGNATURES ON THE FOLLOWING PAGE]

                                       33

<PAGE>

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

ONEOK, INC.                             SUNTRUST BANK, as Purchase Contract
                                        Agent, attorney-in-fact and trustee for
                                        the Holders from time to time of the
                                        Units

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

Address for Notices:                    Address for Notices:

ONEOK, Inc.                             SunTrust Bank
100 West Fifth Street                   25 Park Place
Tulsa, Oklahoma  74603                  24th Floor
Attention: Chief Financial Officer      Atlanta, Georgia  30303
Telecopy: (918) 588-7971                Attention:  Corporate Trust
                                        Administration
                                        Telecopy: (404) 588-7335

_____________________, as Collateral
Agent, Custodial Agent and Securities
Intermediary

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

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

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

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

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

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

                                       34

<PAGE>

EXHIBIT A

                                   INSTRUCTION
                          FROM PURCHASE CONTRACT AGENT
                               TO COLLATERAL AGENT
                          (Creation of Treasury Units)

------------------
Collateral Agent

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

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

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

          Re: _________ Corporate Units of ONEOK, Inc. (the "Company")

          The securities account of __________________, as Collateral Agent,
maintained by the Securities Intermediary and designated "__________________, as
Collateral Agent of ONEOK, Inc., as pledgee of SunTrust Bank, as the Purchase
Contract Agent, attorney-in-fact and trustee for the Holders" (the "Collateral
Account")

          Please refer to the Pledge Agreement, dated as of ________ ___, ____
(the "Pledge Agreement"), among the Company, you, as Collateral Agent, as
Securities Intermediary and as Custodial Agent and the undersigned, as Purchase
Contract Agent, attorney-in-fact and trustee for the holders of Corporate Units
from time to time. Capitalized terms used herein but not defined shall have the
meaning set forth in the Pledge Agreement.

          We hereby notify you in accordance with Section 4.02 of the Pledge
Agreement that the holder of securities named below (the "Holder") has elected
to substitute $_________ Value of Treasury Securities or security entitlements
with respect thereto in exchange for an equal Value of Pledged Subordinated
Notes relating to ________ Corporate Units and has delivered to the undersigned
a notice stating that the Holder has Transferred such Treasury Securities or
security entitlements with respect thereto to the Securities Intermediary, for
credit to the Collateral Account.

          We hereby request that you instruct the Securities Intermediary, upon
confirmation that such Treasury Securities or security entitlements thereto have
been credited to the Collateral Account, to release to the undersigned an equal
Value of Pledged Subordinated Notes in accordance with Section 4.02 of the
Pledge Agreement.

Date:                                   SunTrust Bank, as Purchase Contract
                                        Agent, attorney-in-fact and trustee for
                                        the Holders from time to time of the
                                        Units

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

                                       35

<PAGE>

Please print name and address of Holder electing to substitute Treasury
Securities or security entitlements with respect thereto for the Pledged
Subordinated Notes:


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

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

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

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

                                       36

<PAGE>

EXHIBIT B

                                   INSTRUCTION
                              FROM COLLATERAL AGENT
                           TO SECURITIES INTERMEDIARY
                          (Creation of Treasury Units)

------------------
as Securities Intermediary

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

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

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

          Re:  _________ Corporate Units of ONEOK, Inc. (the "Company")

          The securities account of ____________________________, as Collateral
Agent, maintained by the Securities Intermediary and designated
"____________________________, as Collateral Agent of ONEOK, Inc., as pledgee of
____________________________, as the Purchase Contract Agent, attorney-in-fact
and trustee for the Holders" (the "Collateral Account")

          Please refer to the Pledge Agreement, dated as of ________ ___, ____
(the "Pledge Agreement"), among the Company, you, as Collateral Agent, as
Securities Intermediary and as Custodial Agent and the undersigned, as Purchase
Contract Agent, attorney-in-fact and trustee for the holders of Corporate Units
from time to time. Capitalized terms used herein but not defined shall have the
meaning set forth in the Pledge Agreement.

          When you have confirmed that $__________ Value of Treasury Securities
or security entitlements thereto has been credited to the Collateral Account by
or for the benefit of _________, as Holder of Corporate Units (the "Holder"),
you are hereby instructed to release from the Collateral Account an equal Value
of Pledged Subordinated Notes or security entitlements with respect thereto
relating to _____ Corporate Units of the Holder by Transfer to the Purchase
Contract Agent.

Dated: _______________________

                                        __________________, as Collateral Agent

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

                                       37

<PAGE>

Please print name and address of Holder:


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

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

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

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

                                       38

<PAGE>

EXHIBIT C

                                   INSTRUCTION
                          FROM PURCHASE CONTRACT AGENT
                               TO COLLATERAL AGENT
                        (Recreation of Corporate Units )

SunTrust Bank
The Purchase Contract Agent
25 Park Place
24/th/ Floor
Atlanta, Georgia  30303
Attention: Corporate Trust Administration
Telecopy: (404) 588-7335

          Re:  ____________ Treasury Units of ONEOK, Inc. (the "Company")

          Please refer to the Pledge Agreement dated as of ________ ___, ____
(the "Pledge Agreement"), among the Company, you, as Collateral Agent, as
Securities Intermediary, as Custodial Agent and the undersigned, as Purchase
Contract Agent, attorney-in-fact and trustee for the holders of Treasury Units
from time to time. Capitalized terms used herein but not defined shall have the
meaning set forth in the Pledge Agreement.

          We hereby notify you in accordance with Section 4.03 of the Pledge
Agreement that the holder of securities named below (the "Holder") has elected
to substitute $_______ Value of Subordinated Notes or security entitlements with
respect thereto in exchange for $__________ Value of Pledged Treasury Securities
and has delivered to the undersigned a notice stating that the holder has
Transferred such Subordinated Notes or security entitlements with respect
thereto to the Securities Intermediary, for credit to the Collateral Account.

          We hereby request that you instruct the Securities Intermediary, upon
confirmation that such Subordinated Notes or security entitlements with respect
thereto have been credited to the Collateral Account, to release to the
undersigned $__________ Value of Treasury Securities or security entitlements
with respect thereto related to _____ Treasury Units of such Holder in
accordance with Section 4.03 of the Pledge Agreement.

Dated:  _______________________

                                        __________________, as Collateral Agent

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

                                       39

<PAGE>

Please print name and address of Holder electing to substitute Subordinated
Notes or security entitlements with respect thereto for Pledged Treasury
Securities:


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

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

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

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

                                       40

<PAGE>

EXHIBIT D

                                   INSTRUCTION
                              FROM COLLATERAL AGENT
                           TO SECURITIES INTERMEDIARY
                         (Recreation of Corporate Units)

------------------
as Securities Intermediary

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

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

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

          Re:  ___________ Treasury Units of ONEOK, Inc. (the "Company")

          The securities account of __________________, as Collateral Agent,
maintained by the Securities Intermediary and designated "__________________, as
Collateral Agent of ONEOK, Inc., as pledgee of SunTrust Bank, as the Purchase
Contract Agent, attorney-in-fact and trustee for the Holders" (the "Collateral
Account")

          Please refer to the Pledge Agreement dated as of ________ ___, ____
(the "Pledge Agreement"), among the Company, you, as Securities Intermediary,
Custodial Agent and Collateral Agent and SunTrust Bank, as Purchase Contract
Agent, attorney-in-fact and trustee for the holders of Corporate Units from time
to time, and the undersigned, as Collateral Agent. Capitalized terms used herein
but no defined shall have the meaning set forth in the Pledge Agreement.

          When you have confirmed that $ __________ Value of Subordinated Notes
or security entitlements with respect thereto has been credited to the
Collateral Account by or for the benefit of ________________, as Holder of
Treasury Units (the "Holder"), you are hereby instructed to release from the
Collateral Account $ __________ Value of Treasury Securities or security
entitlements thereto by Transfer to the Purchase Contract Agent.

Dated:  _______________________

                                        __________________, as Collateral Agent

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

                                       41

<PAGE>

Please print name and address of Holder:


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

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

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

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

                                       42

<PAGE>

EXHIBIT E

                    NOTICE OF CASH SETTLEMENT FROM COLLATERAL
                        AGENT TO PURCHASE CONTRACT AGENT
                            (Cash Settlement Amounts)

SunTrust Bank
The Purchase Contract Agent
25 Park Place
24/th/ Floor
Atlanta, Georgia  30303
Attention: Corporate Trust Administration
Telecopy: (404) 588-7335

          Re:  __________  Corporate Units of ONEOK, Inc. (the "Company")
__________ Treasury Units of the Company

          Please refer to the Pledge Agreement dated as of ________ ___, ____
(the "Pledge Agreement"), by and among you, the Company, and SunTrust Bank, as
Collateral Agent, Custodial Agent and Securities Intermediary. Unless otherwise
defined herein, terms defined in the Pledge Agreement are used herein as defined
therein.

          In accordance with Section 4.05(d) of the Pledge Agreement, we hereby
notify you that as of 11:00 a.m. (New York City time) on the fourth Business Day
immediately preceding ________ ___, ____ (the "Purchase Contract Settlement
Date"), we have received (i) $ _______________ in immediately available funds
paid in an aggregate amount equal to the Purchase Price due to the Company on
the Purchase Contract Settlement Date with respect to ________________ Corporate
Units, (ii) $ ___________ in immediately available funds paid in an aggregate
amount equal to the Purchase Price due to the Company on the Purchase Contract
Settlement Date with respect to ______ Treasury Units and (iii) based on the
funds received set forth in clause (i) above, an aggregate principal amount of
$_________ of Pledged Subordinated Notes are to be tendered for purchase in the
Final Remarketing.

Dated:  _______________________

                                        __________________, as Collateral Agent

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

                                       43

<PAGE>

EXHIBIT F

              INSTRUCTION TO CUSTODIAL AGENT REGARDING REMARKETING

------------------
The Custodial Agent

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

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

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

          Re:  Subordinated Notes Due ________ ___, ____ of ONEOK, Inc.
(the "Company")

          The undersigned hereby notifies you in accordance with Section 4.07(c)
of the Pledge Agreement, dated as of ________ ___, ____ (the "Pledge
Agreement"), among the Company, you, as Collateral Agent, Custodial Agent and
Securities Intermediary and SunTrust Bank, as the Purchase Contract Agent,
attorney-in-fact and trustee for the holders of Corporate Units from time to
time, that the undersigned elects to deliver $______________ aggregate principal
amount of Separate Subordinated Notes for delivery to the Remarketing Agent
prior to 5:00 p.m. (New York City time) on the fifth Business Day immediately
preceding the [Initial][Final] Remarketing Date for remarketing pursuant to
Section 4.07(c) of the Pledge Agreement. The undersigned will, upon request of
the Remarketing Agent, execute and deliver any additional documents deemed by
the Remarketing Agent or by the Company to be necessary or desirable to complete
the sale, assignment and transfer of the Separate Subordinated Notes tendered
hereby. Capitalized terms used herein but not defined shall have the meaning set
forth in the Pledge Agreement.

          The undersigned hereby instructs you, upon receipt of the Proceeds of
such remarketing from the Remarketing Agent, to deliver such Proceeds to the
undersigned in accordance with the instructions indicated herein under "A.
Payment Instructions." The undersigned hereby instructs you, in the event of a
Failed Remarketing, upon receipt of the Separate Subordinated Notes tendered
herewith from the Remarketing Agent, to deliver such Separate Subordinated Notes
to the person(s) and the address(es) indicated herein under "B. Delivery
Instructions."

          With this notice, the undersigned hereby (i) represents and warrants
that the undersigned has full power and authority to tender, sell, assign and
transfer the Separate Subordinated Notes tendered hereby and that the
undersigned is the record owner of any Subordinated Notes tendered herewith in
physical form or a participant in The Depositary Trust Company ("DTC") and the
beneficial owner of any Subordinated Notes tendered herewith by book-entry
transfer to your account at DTC, (ii) agrees to be bound by the terms and
conditions of Section 4.07(c) of the Pledge Agreement and (iii) acknowledges and
agrees that after 5:00 p.m. (New York City time) on the fifth Business Day
immediately preceding the [Initial][Final] Remarketing Date, such election shall
become an irrevocable election to have such Separate Subordinated Notes
remarketed in the Remarketing, and that the Separate Subordinated Notes tendered
herewith will only be returned in the event of a Failed Remarketing.

                                       44

<PAGE>

Dated: ____________________

                                        By:
                                           -------------------------------------
                                        Name:
                                        Title:
                                        Signature Guarantee:
                                                            --------------------


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

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

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

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

A.   PAYMENT INSTRUCTIONS

Proceeds of the remarketing should be paid by check in the name of the person(s)
set forth below and mailed to the address set forth below.

Name(s)

(Please Print)
Address

(Please Print)

(Zip Code)

(Tax Identification or Social Security Number)

                                       45

<PAGE>

B.   DELIVERY INSTRUCTIONS

In the event of a Failed Final Remarketing, Subordinated Notes which are in
physical form should be delivered to the person(s) set forth below and mailed to
the address set forth below.

Name(s)

(Please Print)
Address

(Please Print)

(Zip Code)

(Tax Identification or Social Security Number)

In the event of a failed final remarketing, Subordinated Notes which are in
book-entry form should be credited to the account at The Depository Trust
Company set forth below.

------------------
DTC Account Number

Name of Account Party:___________________________

                                       46

<PAGE>

EXHIBIT G

                    INSTRUCTION TO CUSTODIAL AGENT REGARDING
                           WITHDRAWAL FROM REMARKETING

------------------
The Custodial Agent

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

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

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

          Re:  Subordinated Notes Due ________ ___, ____ of ONEOK, Inc.
(the "Company")

          The undersigned hereby notifies you in accordance with Section 4.07(c)
of the Pledge Agreement, dated as of ________ ___, ____ (the "Pledge
Agreement"), among the Company and you, as Collateral Agent, Custodial Agent and
Securities Intermediary, and SunTrust Bank, as Purchase Contract Agent,
attorney-in-fact and trustee for the holders of Corporate Units from time to
time, that the undersigned elects to withdraw the $_________ aggregate principal
amount of Separate Subordinated Notes delivered to the Collateral Agent on
_________, _____ for remarketing pursuant to Section 4.07(c) of the Pledge
Agreement. The undersigned hereby instructs you to return such Subordinated
Notes to the undersigned in accordance with the undersigned's instructions. With
this notice, the Undersigned hereby agrees to be bound by the terms and
conditions of Section 4.07(c) of the Pledge Agreement. Capitalized terms used
herein but not defined shall have the meaning set forth in the Pledge Agreement.

Dated: ____________________

                                        By:
                                           ------------------------------
                                        Name:
                                        Title:
                                        Signature Guarantee:
                                                            --------------------


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

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

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