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                                                                    EXHIBIT 4.13



                          Supplemental Indenture No. 1


               This Supplemental Indenture No. 1, dated as of March 6, 1998 (the
"Supplemental Indenture"), between Beckman Instruments, Inc. (together with its
successors and assigns, the "Company") and The First National Bank of Chicago
(the "Trustee"), as Trustee under the Indenture referred to below.


                               W I T N E S S E T H

               WHEREAS, the Company and the Trustee have heretofore become
parties to an Indenture, dated as of May 15, 1996 (as amended, supplemented,
waived or otherwise modified, the "Indenture");

               WHEREAS, pursuant to an officer's certificate dated May 30, 1996
(the "Officer's Certificate"), the Company established a series of securities
providing for the issuance of an aggregate principal amount of $100,000,000 of
7.05% Debentures due June 1, 2026 (the "Debentures");

               WHEREAS, pursuant to the Debentures, the Company is required, at
the option of the Holder, to repay all or any part of such Holder's Debentures
on June 1, 2006;

               WHEREAS, pursuant to Section 901 of the Indenture, the parties
hereto are authorized to execute and deliver this Supplemental Indenture to
amend the Indenture, without the consent of any Holder;

               NOW, THEREFORE, in consideration of the foregoing and for other
good and valuable consideration, the receipt of which is hereby acknowledged,
the Company and the Trustee mutually covenant and agree for the benefit of the
Holders of the Securities as follows:


                                   ARTICLE I.
                                   DEFINITIONS

SECTION 1.1.   DEFINED TERMS.

               Capitalized terms used herein and not otherwise defined herein
have the meanings assigned to them in the Indenture. The words "herein,"
"hereof" and "hereby" and other words of similar import used in this
Supplemental Indenture refer to this Supplemental Indenture as a whole and not
to any particular section hereof.



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                                   ARTICLE II.
                AMENDMENTS TO CERTAIN PROVISIONS OF THE INDENTURE

SECTION 2.1.   AMENDMENT OF THE DEBENTURES.

               The second full paragraph on page 3 of the face of the Debentures
is hereby deleted in its entirety and replaced with the following paragraph:

               "Subject to and upon compliance with the provisions set forth
        herein, each Holder shall have the right, at such Holder's option, to
        require the Company to repay, and if such right is exercised the Company
        shall repay, all or any part of such Holder's Securities on June 1, 2006
        (the Repayment Date") at a price (the "Repayment Price") equal to
        103.900% of the principal amount thereof, together with accrued interest
        to June 1, 2006."

SECTION 2.2.   AMENDMENT OF SECTION 101 OF THE INDENTURE.

               Section 101 of the Indenture is hereby amended to add the
following definitions:

               "`Bank Indebtedness' means any and all Indebtedness or other
        amounts, whether outstanding on the Issue Date or thereafter incurred,
        payable under or in respect of the Credit Facility or any refundings,
        refinancings, restructurings, replacements, renewals, increases or
        extensions in respect thereof, including in each case (without
        limitation) principal, premium (if any), interest (including interest
        accruing on or after the filing of any petition in bankruptcy or for
        reorganization relating to the Company or any Subsidiary whether or not
        a claim for post-filing interest is allowed in such proceedings), fees,
        charges, expenses, reimbursement obligations, Guarantees, other monetary
        obligations of any nature and all other amounts payable under or in
        respect of any of the foregoing."

               "`Capital Lease Obligation' of any Person means, at the time any
        determination thereof is to be made, the amount of the liability in
        respect of a capital lease for property leased by such Person that would
        at such time be required to be capitalized on the balance sheet of such
        Person in accordance with GAAP."

               "`Capital Stock' of any Person means (i) in the case of a
        corporation, corporate stock, (ii) in the case of an association,
        limited liability company or business entity, any and all Equity
        Interests, (iii) in the case of a partnership, partnership interests
        (whether general or limited) and (iv) any other interest or
        participation that confers on a Person the right to receive a share of
        the profits and losses of, or distributions of assets of, the issuing
        Person, including any Preferred Stock."

               "`Commodity Price Protection Agreement' means any forward
        contract, commodity swap, commodity option or other similar financial
        agreement or



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        arrangement relating to, or the value which is dependent upon,
        fluctuations in commodity prices."

               "`Credit Agreement' means the credit agreement dated as of
        October 31, 1997, among the Company, the banks and other financial
        institutions party thereto from time to time, Citicorp USA, Inc., as
        agent, Citicorp Securities, Inc., as arranger, and Merrill Lynch & Co.,
        as syndication agent, as such agreement may be amended, supplemented,
        waived or otherwise modified from time to time, or refunded, refinanced,
        restructured, replaced, renewed, repaid, increased or extended from time
        to time (whether in whole or in part, whether with the original agents
        and lenders or other agents and lenders or otherwise, and whether
        provided under the original Credit Agreement or otherwise)."

               "`Credit Facility' means the collective reference to the Credit
        Agreement, any notes and letters of credit issued pursuant thereto and
        any guarantees, security agreements, pledges, mortgages, letter of
        credit applications and other collateral documents, and other
        instruments and documents, executed and delivered pursuant to or in
        connection with any of the foregoing, in each case as the same may be
        amended, supplemented, waived or otherwise modified from time to time,
        or refunded, refinanced, restructured, replaced, renewed, repaid,
        increased or extended from time to time (whether in whole or in part,
        whether with the original agents and lenders or other agents and lenders
        or otherwise, and whether provided under the original Credit Agreement
        or otherwise)."

               "`Currency Hedging Arrangements' means one or more of the
        following agreements which shall be entered into by one or more
        financial institutions: foreign exchange contracts, currency swap
        agreements or other similar agreements or arrangements designed to
        protect against the fluctuations in currency values."

               "`Debenture Guarantee' means each Guarantee of the Debentures by
        the Debenture Guarantors and any Guarantee of the Debentures that may
        from time to time be executed and delivered pursuant to the terms of the
        Indenture. Each such Debenture Guarantee shall be in the form prescribed
        by the Indenture."

               "`Debenture Guarantors' means each of Coulter Corporation,
        Beckman Instruments (Naguabo) Inc., Hybritech Incorporated, SmithKline
        Diagnostics, Inc. and Coulter Leasing Corporation and any Subsidiary
        that has issued a Debenture Guarantee."

               "`Disqualified Stock' means (i) any Preferred Stock of any
        Subsidiary and (ii) any Capital Stock that, by its terms (or by the
        terms of any security into which it is convertible or for which it is
        exchangeable), or upon the happening of any event, matures or is
        mandatorily redeemable, pursuant to a sinking fund obligation or



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        otherwise, or is redeemable at the option of the holder thereof (other
        than upon a change of control of the Company in circumstances where the
        holders of the Debentures would have similar rights), in whole or in
        part on or prior to the stated maturity of any Debentures."

               "`Equity Interest' in any Person means any and all shares,
        interests, rights to purchase, warrants, options, participations or
        other equivalents of or interests in (however designated) corporate
        stock or other equity participations, including limited liability
        company interests, in such Person."

               "`GAAP' means, with respect to any series of Securities,
        generally accepted accounting principles in the United States of America
        as in effect on the date of original issuance of such series of
        Securities, including those set forth in the opinions and pronouncements
        of the Accounting Principles Board of the American Institute of
        Certified Public Accountants and statements and pronouncements of the
        Financial Accounting Standards Board or in such other statement by such
        other entity as approved by a significant segment of the United States
        accounting profession."

               "`Guarantee' means any obligation, contingent or otherwise, of
        any Person directly or indirectly guaranteeing any Indebtedness or other
        obligation of any other Person, and any obligation, direct or indirect,
        contingent or otherwise, of such Person (i) to purchase or pay (or
        advance or supply funds for the purchase or payment of) such
        Indebtedness or other obligation of such Person (whether arising by
        virtue of partnership arrangements, or by agreement to keep well, to
        purchase assets, goods, securities or services, to take-or-pay, or to
        maintain financial statement conditions or otherwise) or (ii) entered
        into for purposes of assuring in any other manner the obligee of such
        Indebtedness or other obligation of the payment thereof or to protect
        such obligee against loss in respect thereof (in whole or in part),
        provided, however, that the term `Guarantee' shall not include
        endorsements for collection or deposit in the ordinary course of
        business. The term `Guarantee' used as a verb has a corresponding
        meaning."

               "`Indebtedness' means, with respect to any Person, without
        duplication, and whether or not contingent, (i) all indebtedness of such
        Person for borrowed money or which is evidenced by a note, bond,
        debenture or similar instrument, (ii) all obligations of such Person to
        pay the deferred or unpaid purchase price of property or services, which
        purchase price is due more than one year after the date of placing such
        property in service or taking delivery and title thereto or the
        completion of such service, (iii) all Capital Lease Obligations of such
        Person, (iv) all obligations of such Person in respect of letters of
        credit or bankers' acceptances issued or created for the account of such
        Person, (v) to the extent not otherwise included in this definition, all
        net obligations of such Person under all Interest Rate Agreement,
        Currency Hedging Arrangements or Commodity Price Protection Agreements
        of such Person, (vi) all liabilities of others of



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        the kind described in the preceding clause (i), (ii) or (iii) secured by
        any Lien on any property owned by such Person even if such Person has
        not assumed or otherwise become liable for the payment thereof, to the
        extent of the value of the property subject to such Lien, (vii) all
        Disqualified Stock issued by such Person, and (viii) to the extent not
        otherwise included, any Guarantee by such Person of any other Person's
        indebtedness or other obligations described in clauses (i) through (vii)
        above. `Indebtedness' of the Company and its Subsidiaries shall not
        include (i) current trade payables incurred in the ordinary course of
        business and payable in accordance with customary practices and (ii)
        non-interest bearing installment obligations and accrued liabilities
        incurred in the ordinary course of business which are not more than 90
        days past due."

               "`Indenture Obligations' means the obligations of the Company and
        any other obligor under this Indenture or under the Securities, to pay
        principal of, premium, if any, and interest on the Securities when due
        and payable, whether at maturity, by acceleration, call for redemption
        or repurchase or otherwise , and all other amounts due or to become due
        under or in connection with this Indenture, the Securities or the
        Debenture Guarantees and the performance of all other obligations to the
        Trustee (including, but not limited to, payment of all amounts due the
        Trustee under Section 607 of the Indenture) and the Holders of the
        Securities of either series under this Indenture, the Securities and the
        Debenture Guarantees, according to the terms thereof."

               "`Interest Rate Agreements' means one or more of the following
        agreements which shall be entered into by one or more financial
        institutions: interest rate protection agreements (including, without
        limitation, interest rate swaps, caps, floors, collars and similar
        agreements) and/or other types of interest rate hedging agreements from
        time to time."

               "`Issue Date' means, with respect to the Company's 7.05%
        Debentures due 2026, March 6, 1998, and means, with respect to any other
        series of Securities, the date of original issuance of such series of
        Securities."

               "`Preferred Stock' as applied to the Capital Stock of any Person,
        means Capital Stock of any class or classes (however designated) which
        is preferred as to the payment of dividends or distributions, or as to
        the distribution of assets upon any voluntary or involuntary liquidation
        or dissolution of such Person, over Capital Stock of any other class of
        such Person."

               "`Stated Maturity' means, when used in any supplemental indenture
        executed pursuant to Section 1011, the date specified in such security
        as the fixed date on which the payment of principal of such security is
        due and payable, including pursuant to any mandatory redemption
        provision (but excluding any provision providing for the



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        purchase of such security at the option of the holder thereof upon the
        happening of any contingency beyond the control of the issuer unless
        such contingency has occurred). `Stated Maturity' shall otherwise have
        the meaning set forth in the Indenture."

               "`Subsidiary' of a Person means, for purposes of Section 1011 and
        when used in any supplemental indenture executed pursuant thereto, a
        Person more than 50% of the outstanding voting stock or other Equity
        Interests of which is owned, directly or indirectly, by the Company or
        by one or more other Subsidiaries, or by the Company and one or more
        other Subsidiaries. For the purposes of this definition, "voting" stock
        or other Equity Interests means stock or other Equity Interests which
        ordinarily has voting power for the election of directors, trustees or
        similar managers, whether at all times or only so long as no senior
        class of stock or other Equity Interests has such voting power by reason
        of any contingency. `Subsidiary,' shall otherwise have the meaning set
        forth in the Indenture."

SECTION 2.3.   AMENDMENT OF ARTICLE TEN OF THE INDENTURE.

               Article Ten of the Indenture is hereby amended to add the
following paragraph in its entirety immediately following the text of SECTION
1010:

        "SECTION 1011.Future Debenture Guarantors."

               "The Company may elect, at its option at any time, to have this
        Section 1011 apply to any Securities or any series of Securities, in
        accordance with the requirements set forth below in this Section. The
        Company hereby elects to have this Section 1011 apply to the
        Debentures."

               "The Company will cause each Subsidiary that Guarantees any Bank
        Indebtedness promptly to execute and deliver to the Trustee a
        supplemental indenture substantially in the form set forth in Exhibit A
        to this Indenture pursuant to which such Subsidiary will guarantee the
        Company's obligations under the Indenture and the Securities of each
        series, in accordance with and as further provided in such supplemental
        indenture. Concurrently therewith, the Company shall deliver to the
        Trustee an Opinion of Counsel in form and substance reasonably
        satisfactory to the Trustee to the effect that such supplemental
        indenture has been duly authorized, executed and delivered by such
        Subsidiary and that, subject to the applicable bankruptcy, insolvency,
        fraudulent transfer, fraudulent conveyance, reorganization, moratorium
        and other laws now or hereafter in effect affecting creditors' rights or
        remedies generally and the general principles of equity, such
        supplemental indenture is a valid and binding agreement of such
        Subsidiary, enforceable against such Subsidiary in accordance with its
        terms."



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SECTION 2.4.   AMENDMENT OF THE INDENTURE ADDING EXHIBIT A.

               The Indenture is hereby amended to add Exhibit A hereto in its
entirety, as the form of Exhibit A to the Indenture.

                                  ARTICLE III.
                                  MISCELLANEOUS

SECTION 3.1.   PARTIES.

               Nothing in this Supplemental Indenture is intended or shall be
construed to give any Person, other than the Holders and the Trustee, any legal
or equitable right, remedy or claim under any provision contained herein.

SECTION 3.2.   GOVERNING LAW.

               THIS SUPPLEMENTAL INDENTURE SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK (WITHOUT GIVING EFFECT TO THE
CONFLICT OF LAWS PRINCIPLES THEREOF, OTHER THAN ANY MANDATING THE APPLICATION OF
SUCH LAWS).

SECTION 3.3.   RATIFICATION OF INDENTURE; SUPPLEMENTAL INDENTURES PART OF
               INDENTURE.

               Except as expressly amended hereby, the Indenture is in all
respects ratified and confirmed and all the terms, conditions and provisions
thereof shall remain in full force and effect. This Supplemental Indenture shall
form a part of the Indenture for all purposes, and every Holder of Securities
heretofore or hereafter authenticated and delivered shall be bound hereby. The
Trustee makes no representation or warranty as to the validity or sufficiency of
this Supplemental Indenture.

SECTION 3.4.   COUNTERPARTS.

               The parties hereto may sign one or more copies of this
Supplemental Indenture in counterparts, all of which together shall constitute
one and the same agreement.

SECTION 3.5.   HEADINGS.

               The section headings herein are for convenience of reference only
and shall not be deemed to alter or affect the meaning or interpretation of any
provisions hereof.



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               IN WITNESS WHEREOF, the parties hereto have caused this
Supplemental Indenture to be duly executed, and their respective corporate seals
to be hereunto affixed and attested, all as of the date first above written.

                                        BECKMAN INSTRUMENTS, INC.


                                        By:  /s/ Dennis K. Wilson
                                             -----------------------------------
                                             Name:  Dennis K. Wilson
                                             Title: Vice President, Finance and
Attest:                                             Chief Financial Officer


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


                                        THE FIRST NATIONAL BANK OF CHICAGO


                                        By:  /s/ Leland Hansen
                                             -----------------------------------
                                             Name:  Leland Hansen
Attest:                                      Title: Assistant Vice President


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



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                                                                       Exhibit A

        Form of Supplemental Indenture in Respect of Debenture Guarantee

               This Supplemental Indenture, dated as of [___________] (this
"Supplemental Indenture.), among [name of Debenture Guarantor(s)] (the
"Debenture Guarantor(s)"), [Company] (together with its successors and assigns,
the "Company"), each other then existing Subsidiary Guarantor under the
Indenture referred to below, and [Trustee], as Trustee under the Indenture
referred to below.

                               W I T N E S S E T H

               WHEREAS, the Company and the Trustee have heretofore become
parties to an Indenture, dated as of May 15, 1996 (as amended, supplemented,
waived or otherwise modified, the "Indenture");

               WHEREAS, Section 1011 of the Indenture provides that under
certain circumstances the Company is required to cause a Debenture Guarantor to
execute and deliver to the Trustee a supplemental indenture pursuant to which
the Debenture Guarantor shall guarantee the Company's obligations under the a
series of Securities pursuant to a Debenture Guarantee on the terms and
conditions set forth herein; and

               WHEREAS, the Debenture Guarantors are executing this Supplemental
Indenture pursuant to which the Debenture Guarantors will guarantee the
Company's obligations under [name of series of Securities] (the "Securities") on
the terms and conditions set forth herein;

               WHEREAS, pursuant to Sections 901 and 1011 of the Indenture, the
parties hereto are authorized to execute and deliver this Supplemental Indenture
to amend the Indenture, without the consent of any Holder;

               NOW, THEREFORE, in consideration of the foregoing and for other
good and valuable consideration, the receipt of which is hereby acknowledged,
the Debenture Guarantor, the Company, the other Debenture Guarantors, if any,
and the Trustee mutually covenant and agree for the benefit of the Holders of
the Securities as follows:

                                   ARTICLE I.
                                   DEFINITIONS

SECTION 1.1.   DEFINED TERMS.

               Capitalized terms used herein and not otherwise defined herein
have the meanings assigned to them in the Indenture. The words "herein,"
"hereof" and "hereby" and



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other words of similar import used in this Supplemental Indenture refer to this
Supplemental Indenture as a whole and not to any particular section hereof.

                                   ARTICLE II.
                             AGREEMENT TO GUARANTEE

SECTION 2.1.   AGREEMENT TO GUARANTEE.

               The Debenture Guarantor hereby agrees to be bound by all
applicable provisions of the Indenture as a Debenture Guarantor and to guarantee
the Company's obligations under the Indenture and the Securities on the terms
and subject to the conditions set forth below:

        SECTION 2.1.1 UNCONDITIONAL GUARANTEE.

                      (a) Each Debenture Guarantor hereby jointly and severally
        and fully and unconditionally guarantees to each Holder of a Security
        authenticated and delivered by the Trustee and its successors and
        assigns that: (1) the principal of, and premium, if any, and interest
        on, the Securities of each series will be duly and punctually paid in
        full when due, whether at maturity, by acceleration or otherwise, and
        interest on the overdue principal and (to the extent permitted by law)
        interest, if any, on the Securities of each series and all other
        obligations of the Company or the Debenture Guarantors to the Holders or
        the Trustee hereunder and thereunder (including fees, expenses or other)
        and all other Indenture Obligations will be promptly paid in full or
        performed, all in accordance with the terms hereof; and (2) in case of
        any extension of time of payment or renewal of any Securities of either
        series or any of such other Indenture Obligations with respect to the
        Securities of either series, the same will be promptly paid in full when
        due in accordance with the terms of the extension or renewal, whether at
        Stated Maturity, by acceleration or otherwise. Failing payment when due
        of any amount so guaranteed, or failing performance of any other
        obligation of the Company to the Holders of Securities of either series,
        for whatever reason, each Debenture Guarantor will be obligated to pay
        or cause the payment of, or to perform or cause the performance of, the
        same immediately. An Event of Default under this Indenture or the
        Securities of either series shall constitute an event of default under
        this Debenture Guarantee, and shall entitle the Holders of Securities of
        such series to accelerate the obligations of the Debenture Guarantor
        hereunder in the same manner and to the same extent as the obligations
        of the Company.

                      Each Debenture Guarantor hereby agrees that its
        obligations hereunder shall be unconditional, irrespective of the
        validity, regularity or enforceability of this Indenture, the Securities
        of either series or the obligations of the Company or any other
        Debenture Guarantor to the Holders or the Trustee hereunder or
        thereunder, the absence of any action to enforce the same, any waiver or
        consent by any Holder of Securities with respect to any provisions
        hereof or thereof, any release of any other Debenture Guarantor, the
        recovery of any judgment against the Company, any action to



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        enforce the same, whether or not a Debenture Guarantee is affixed to any
        particular Security, or any other circumstance which might otherwise
        constitute a legal or equitable discharge or defense of a guarantor.

                      Each Debenture Guarantor hereby waives the benefit of
        diligence, presentment, demand of payment, filing of claims with a court
        in the event of insolvency or bankruptcy of the Company, any right to
        require a proceeding first against the Company, protest, notice and all
        demands whatsoever and covenants that (except as otherwise provided in
        Section 2.1.2) its Debenture Guarantee will not be discharged except by
        complete performance of the obligations contained in the Securities,
        this Indenture and this Debenture Guarantee. This Debenture Guarantee is
        a guarantee of payment and not of collection. Each Debenture Guarantor
        further agrees that, as between it, on the one hand, and the Holders of
        Securities and the Trustee, on the other hand (1) subject to this
        Section 2.1, the maturity of the obligations guaranteed hereby may be
        accelerated as and to the extent provided in Article Five of the
        Indenture for the purposes of this Debenture Guarantee, notwithstanding
        any stay, injunction or other prohibition preventing such acceleration
        in respect of the obligations guaranteed hereby, and (2) in the event of
        any acceleration of such obligations as provided in Article Five of the
        Indenture, such obligations (whether or not due and payable) shall
        forthwith become due and payable by such Debenture Guarantor for the
        purpose of this Debenture Guarantee. Neither the Trustee nor any other
        Person shall have any obligation to enforce or exhaust any rights or
        remedies or to take any other steps under any security for the Indenture
        Obligations or against the Company or any other Person or any property
        of the Company or any other Person before the Trustee is entitled to
        demand payment and performance by any or all Debenture Guarantors of
        their liabilities and obligations under their respective Debenture
        Guarantees or under this Indenture.

                      Until terminated in accordance with Section 2.1.2, this
        Debenture Guarantee shall remain in full force and effect and continue
        to be effective should any petition be filed by or against the Company
        for liquidation or reorganization, should the Company become insolvent
        or make an assignment for the benefit of creditors or should a receiver
        or trustee be appointed for all or any significant part of the Company's
        assets, and shall, to the fullest extent permitted by law, continue to
        be effective or be reinstated, as the case may be, if at any time
        payment and performance of the Securities of either series are, pursuant
        to applicable law, rescinded or reduced in amount, or must otherwise be
        restored or returned by any obligee on such Securities, whether as a
        "voidable preference," "fraudulent transfer" or otherwise, all as though
        such payment or performance had not been made. In the event that any
        payment, or any part thereof, is rescinded, reduced, restored or
        returned, the Securities of the relevant series shall, to the fullest
        extent permitted by law, be reinstated and deemed reduced only by such
        amount paid and not so rescinded, reduced, restored or returned.



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                      (b) Each Debenture Guarantor that makes a payment or
        distribution under this Debenture Guarantee shall have the right to seek
        contribution from any non-paying Debenture Guarantor so long as the
        exercise of such right does not impair the rights of the Holders under
        this Debenture Guarantee.

                      (c) Notwithstanding any of the foregoing, each Debenture
        Guarantor's liability under this Debenture Guarantee shall be limited to
        the maximum amount that would not result in this Debenture Guarantee
        constituting a fraudulent conveyance or fraudulent transfer under
        applicable law.

                      (d) Each Debenture Guarantor acknowledges that it will
        receive direct and indirect benefits from the financing arrangements
        contemplated by this Indenture and that its Debenture Guarantee, and the
        waiver set forth in Section 2.1.3, is knowingly made in contemplation of
        such benefits.

        SECTION 2.1.2. RELEASE OF A DEBENTURE GUARANTEE.

                      (a) Any Debenture Guarantor shall be automatically and
        unconditionally released and discharged from all of its obligations
        under its Debenture Guarantee, and such Debenture Guarantee shall
        terminate, at any such time that such Debenture Guarantor is released
        and discharged from all of its obligations under all of its Guarantees
        in respect of Bank Indebtedness, unless such release results from
        payment under such Guarantee. Upon the delivery by the Company to the
        Trustee of an Officers' Certificate and, if requested by the Trustee, an
        Opinion of Counsel to the effect that the transaction giving rise to
        such release of such Debenture Guarantee was made by the Company in
        accordance with the provisions of this Indenture and the Securities, the
        Trustee shall execute any documents reasonably required in order to
        evidence such release and discharge of such Debenture Guarantor from its
        obligations under and termination of its Debenture Guarantee.

                      (b) Upon the sale, exchange or transfer to any Person not
        an Affiliate of the Company of all of the Capital Stock held by the
        Company and its Subsidiaries in, or all or substantially all the assets
        of, a Debenture Guarantor (which sale, exchange or transfer is not
        prohibited by this Indenture), such Debenture Guarantor shall be
        automatically and unconditionally released and discharged from all its
        obligations under its Debenture Guarantee, and such Debenture Guarantee
        shall terminate. Upon such occurrence, the Trustee shall execute any
        documents reasonably required in order to evidence such release,
        discharge and termination in respect of such Debenture Guarantee.

                      (c) Upon the release of any Debenture Guarantor from its
        Debenture Guarantee pursuant to the provisions of the Indenture, each
        other Debenture Guarantor



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        not so released shall remain liable for the full amount of principal of,
        and premium, if any, and interest on, the Securities as and to the
        extent provided in this Section 2.1.

                      (d) Each Debenture Guarantee shall terminate and cease to
        be of further effect upon (i) defeasance of the Company's obligations in
        accordance with Section 1402 of the Indenture and (ii) satisfaction and
        discharge of this Indenture in accordance with Section 401 of the
        Indenture.

        SECTION 2.1.3. WAIVER OF SUBROGATION.

                      Each Debenture Guarantor hereby irrevocably waives any
        claim or other rights which it may now or hereafter acquire against the
        Company that arise from the existence, payment, performance or
        enforcement of the Company's obligations under the Securities of either
        series and this Indenture or such Debenture Guarantor's obligations
        under its Debenture Guarantee and this Indenture, including, without
        limitation, any right of subrogation, reimbursement, exoneration,
        indemnification, and any right to participate in any claim or remedy of
        any Holder of Securities of either series against the Company, whether
        or not such claim, remedy or right arises in equity, or under contract,
        statute or common law, until this Indenture is discharged and all of the
        Securities of both series are discharged and paid in full. If any amount
        shall be paid to any Debenture Guarantor in violation of the preceding
        sentence and the Securities of the relevant series shall not have been
        paid in full, such amount shall have been deemed to have been paid to
        such Debenture Guarantor for the benefit of, and held in trust for the
        benefit of, the Holders of the Securities of such series, and shall
        forthwith be paid to the Trustee for the benefit of such Holders to be
        credited and applied upon such Securities, whether matured or unmatured,
        in accordance with the terms of this Indenture.

        SECTION 2.1.4. RELIANCE ON JUDICIAL ORDER OR CERTIFICATE OF LIQUIDATING
                       AGENT REGARDING DISSOLUTION, ETC.

                      Upon any payment or distribution of assets of any
        Debenture Guarantor referred to in this Section 2.1, the Trustee,
        subject to the provisions of Section 601 of the Indenture, and the
        Holders of Securities of either series shall be entitled to rely upon
        any order or decree entered by any court of competent jurisdiction in
        which such insolvency, bankruptcy, receivership, liquidation,
        reorganization, dissolution, winding-up or similar case or proceeding is
        pending, or a certificate of the trustee in bankruptcy, receiver,
        liquidating trustee, custodian, assignee for the benefit of creditors,
        agent or other Person making such payment or distribution, delivered to
        the Trustee or to such Holders, for the purpose of ascertaining the
        Persons entitled to participate in such payment or distribution, the
        holders of other Indebtedness of such Debenture Guarantor, the amount
        thereof or payable thereon, the amount or amounts paid or distributed
        thereon and all other facts pertinent thereto or to this Section 2.1;
        provided that the foregoing shall apply only if such court has been
        fully apprised of the provisions of this Section 2.1.



                                      A-5
<PAGE>   14

        SECTION 2.1.5. SECTION 2.1 APPLICABLE TO PAYING AGENTS.

                      In case at any time any Paying Agent other than the
        Trustee shall have been appointed by the Company and be then acting
        hereunder, the term `Trustee' as used in this Section 2.1 shall in such
        case (unless the context otherwise requires) be construed as extending
        to and including such Paying Agent within its meaning as fully for all
        intents and purposes as if such Paying Agent were named in this Section
        2.1 in addition to or in place of the Trustee.

        SECTION 2.1.6. NO SUSPENSION OF REMEDIES.

                      Nothing contained in this Section 2.1 shall limit the
        right of the Trustee or the Holders of Securities of either series to
        take any action to accelerate the maturity of such Securities pursuant
        to Article Five of the Indenture or to pursue any rights or remedies
        hereunder or under applicable law.


                                  ARTICLE III.
                                  MISCELLANEOUS

SECTION 3.1.   TERMINATION.

               The Debenture Guarantor's Debenture Guarantee shall terminate and
be of no further force or effect, and the Debenture Guarantor shall be released
and discharged from all obligations in respect of such Debenture Guarantee, as
and when provided in Section 2.1.2.

SECTION 3.2.   PARTIES.

               Nothing in this Supplemental Indenture is intended or shall be
construed to give any Person, other than the Holders and the Trustee, any legal
or equitable right, remedy or claim under or in respect of the Debenture
Guarantor's Debenture Guarantee or any provision contained herein or in Section
2.1.

SECTION 3.3.   GOVERNING LAW.

               THIS SUPPLEMENTAL INDENTURE SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK (WITHOUT GIVING EFFECT TO THE
CONFLICT OF LAWS PRINCIPLES THEREOF, OTHER THAN ANY MANDATING THE APPLICATION OF
SUCH LAWS).

SECTION 3.4.   RATIFICATION OF INDENTURE; SUPPLEMENTAL INDENTURES PART OF
               INDENTURE.



                                      A-6
<PAGE>   15

               Except as expressly amended hereby, the Indenture is in all
respects ratified and confirmed and all the terms, conditions and provisions
thereof shall remain in full force and effect. This Supplemental Indenture shall
form a part of the Indenture for all purposes, and every Holder of Securities
heretofore or hereafter authenticated and delivered shall be bound hereby. The
Trustee makes no representation or warranty as to the validity or sufficiency of
this Supplemental Indenture.

SECTION 3.5.   COUNTERPARTS.

               The parties hereto may sign one or more copies of this
Supplemental Indenture in counterparts, all of which together shall constitute
one and the same agreement.

SECTION 3.6.   HEADINGS.

               The section headings herein are for convenience of reference only
and shall not be deemed to alter or affect the meaning or interpretation of any
provisions hereof.



                                      A-7
<PAGE>   16

               IN WITNESS WHEREOF, the parties hereto have caused this
Supplemental Indenture to be duly executed, and their respective corporate seals
to be hereunto affixed and attested, all as of the date first above written.

                                        [THE COMPANY]


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


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


                                        [THE TRUSTEE]


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


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



                                        [NAME OF GUARANTOR]


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


--------------------------
                                        [Add signature block for any other
                                        existing Debenture Guarantor]



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