<PAGE>   1
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                                                                     EXHIBIT 4.A



                          EL PASO NATURAL GAS COMPANY,

                                                                    Issuer

                                       and




                                 CITIBANK, N.A.,

                                                                   Trustee


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


                                    INDENTURE



                           Dated as of January 1, 1992


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




                                 DEBT SECURITIES








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<PAGE>   2


                           EL PASO NATURAL GAS COMPANY
                              CROSS REFERENCE SHEET

         This Cross Reference Sheet shows the location in this Indenture of the
provisions inserted pursuant to Section 310-318 (a), inculsive of the Trust
Indenture Acto of 1939, as amended. This Cross Reference Sheet shall not, for
any purpose, be deemed to be a part of this Indenture.

<TABLE>
<CAPTION>
Trust Indenture
   Act Section                                       Indenture Section
---------------                                      -----------------
<S>                                                      <C>            
Section 310 (a) (1), (2).................................6.09           
            (a) (3), (4).................................Not Applicable 
            (a) (5)......................................6.09           
            (b)..........................................6.08, 6.10     
            (c)..........................................Not Applicable 
Section 311 (a), (b).....................................6.13           
            (c)..........................................Not Applicable 
Section 312 (a)..........................................7.01, 7.02 (a) 
            (b)..........................................7.02 (b)       
            (c)..........................................7.02 (c)       
Section 313 (a) (1) - (4), (6) - (8).....................7.03 (a)       
            (a) (5)......................................Not Applicable 
            (b) (1)......................................Not Applicable 
            (b) (2)......................................7.03 (b)       
            (c), (d).....................................7.03           
Section 314 (a)..........................................7.04           
            (b)..........................................Not Applicable 
            (c) (1), (2).................................1.03           
            (c) (3)......................................Not Applicable 
            (d)..........................................Not Applicable 
            (e)..........................................1.03           
            (f)..........................................Not Applicable 
Section 315 (a)..........................................6.01 (a)       
            (b)..........................................6.02           
            (c)..........................................6.01 (b)       
            (d)..........................................6.01 (c)       
            (d) (1)......................................6.01 (a)       
            (d) (2)......................................6.01 (c) (2)   
            (d) (3)......................................6.01 (c) (3)   
            (e)..........................................5.14           
Section 316 (a)..........................................1.01           
            (a) (1) (A)..................................5.12           
            (a) (1) (B)..................................5.13           
            (a) (2)......................................Not Applicable 
            (b)..........................................5.08           
</TABLE>



<PAGE>   3


<TABLE>
<S>                                                     <C>             
Section 317 (a) (1)......................................5.03           
            (a) (2)......................................5.04           
            (b)..........................................10.03          
Section 318 (a)..........................................1.08
</TABLE>



<PAGE>   4




                                    CONTENTS

<TABLE>
<S>                                                                                                      <C>
ARTICLE ONE - DEFINITIONS AND OTHER PROVISIONS OF GENERAL
              APPLICATION.................................................................................1
              SECTION 1.01.         Definitions...........................................................1
              SECTION 1.02.         Incorporation by Reference of Trust Indenture Act.....................6
              SECTION 1.03.         Compliance Certificates and Opinions..................................6
              SECTION 1.04.         Form of Documents Delivered to Trustee................................7
              SECTION 1.05.         Acts of Holders.......................................................7
              SECTION 1.06.         Notices, Etc., to Trustee and Company.................................8
              SECTION 1.07.         Notices to Holders; Waiver............................................9
              SECTION 1.08.         Conflict with Trust Indenture Act.....................................9
              SECTION 1.09.         Effect of Headings and Table of Contents..............................9
              SECTION 1.10.         Successors and Assigns................................................9
              SECTION 1.11.         Separability Clause...................................................10
              SECTION 1.12.         Benefits of Indenture.................................................10
              SECTION 1.13.         Governing Law.........................................................10
              SECTION 1.14.         Legal Holidays........................................................10
ARTICLE TWO - FORM OF SECURITIES    10
              SECTION 2.01.         Forms Generally.......................................................10
              SECTION 2.02.         Form of Trustee's Certificate of Authentication.......................11
ARTICLE THREE - THE SECURITIES      11
              SECTION 3.01.         Title and Terms.......................................................11
              SECTION 3.02.         Denominations.........................................................13
              SECTION 3.03.         Execution, Authentication, Delivery and Dating........................14
              SECTION 3.04.         Temporary Securities..................................................15
              SECTION 3.05.         Registration, Registration of Transfer and Exchange...................15
              SECTION 3.06.         Mutilated, Destroyed, Lost and Stolen Securities......................16
              SECTION 3.07.         Payment of Interest; Interest Rights Preserved........................17
              SECTION 3.08.         Persons Deemed Owners.................................................18
              SECTION 3.09.         Cancellation..........................................................18
              SECTION 3.10.         Computation of Interest...............................................19
ARTICLE FOUR - SATISFACTION AND DISCHARGE: UNCLAIMED MONEYS...............................................19
              SECTION 4.01.         Satisfaction and Discharge of Indenture...............................19
              SECTION 4.02.         Deposited Moneys to Be Held in Trust by Trustee.......................21
              SECTION 4.03.         Paying Agent to Repay Moneys Held.....................................21
              SECTION 4.04.         Return of Unclaimed Moneys............................................21
              SECTION 4.05.         Reinstatement.........................................................22
ARTICLE FIVE - REMEDIES             22
              SECTION 5.01.         Events of Default.....................................................22
              SECTION 5.02.         Acceleration of Maturity; Rescission and Annulment....................23
              SECTION 5.03.         Collection of Indebtedness and Suits for
                                    Enforcement by Trustee................................................25
              SECTION 5.04.         Trustee May File Proofs of Claim......................................25
</TABLE>


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<TABLE>
<S>                                                                                                      <C>
              SECTION 5.05.         Trustee May Enforce Claims Without
                                    Possesion of Securities...............................................26
              SECTION 5.06.         Application of Money Collected........................................26
              SECTION 5.07.         Limitation of Suits...................................................27
              SECTION 5.08.         Unconditional Right of Holders to Receive
                                    Principal and Interest................................................27
              SECTION 5.09.         Restoration of Rights and Remedies....................................28
              SECTION 5.10.         Rights and Remedies Cumulative........................................28
              SECTION 5.11.         Delay or Omission Not Waiver..........................................28
              SECTION 5.12.         Control by Holders....................................................28
              SECTION 5.13.         Waiver of Past Defaults...............................................29
              SECTION 5.14.         Undertaking for Costs.................................................29
              SECTION 5.15.         Waiver of Stay or Extension Laws......................................29
ARTICLE SIX - THE TRUSTEE           30
              SECTION 6.01.         Certain Duties and Responsibilities...................................30
              SECTION 6.02.         Notice of Defaults....................................................31
              SECTION 6.03.         Certain Rights of Trustee.............................................31
              SECTION 6.04.         Not Responsible for Recitals or Issuance of Securities................32
              SECTION 6.05.         May Hold Securities...................................................32
              SECTION 6.06.         Money Held in Trust...................................................32
              SECTION 6.07.         Compensation and Reimbursement........................................32
              SECTION 6.08.         Disqualification; Conflicting Interests...............................33
              SECTION 6.09.         Corporate Trustee Required; Eligibility...............................33
              SECTION 6.10.         Resignation and Removal; Appointment of Successor.....................34
              SECTION 6.11.         Acceptance and Appointment by Successor...............................35
              SECTION 6.12.         Merger, Conversion, Consolidation or Succession
                                    to Business...........................................................36
              SECTION 6.13.         Preferential Collection of Claims Against Company.....................36
ARTICLE SEVEN - HOLDERS' LISTS AND REPORTS BY TRUSTEE AND
              COMPANY        .............................................................................36
              SECTION 7.01.         Company to Furnish Trustee Names and
                                    Addresses of Holders..................................................36
              SECTION 7.02.         Preservation of Information; Communication to Holders.................37
              SECTION 7.03.         Reports by Trustee....................................................37
              SECTION 7.04.         Reports by Company....................................................38
ARTICLE EIGHT - CONSOLIDATION, MERGER, CONVEYANCE, TRANSFER OR
              LEASE   38
              SECTION 8.01.         Company May Consolidate, Etc., Only on Certain Terms..................38
              SECTION 8.02.         Successor Corporation Substituted.....................................39
ARTICLE NINE - SUPPLEMENTAL INDENTURES....................................................................39
              SECTION 9.01.         Supplemental Indentures Without Consent of Holders....................39
              SECTION 9.02.         Supplemental Indentures With Consent of Holders.......................40
              SECTION 9.03.         Execution of Supplemental Indentures..................................41
              SECTION 9.04.         Effect of Supplemental Indentures.....................................41
              SECTION 9.05.         Conformity With Trust Indenture Act...................................41
</TABLE>


                                      -ii-
<PAGE>   6



<TABLE>
<S>                                                                                                      <C>
              SECTION 9.06.         Reference in Securities to Supplemental Indentures....................41
ARTICLE TEN - COVENANTS             42
              SECTION 10.01.        Payment of Principal and Interest.....................................42
              SECTION 10.02.        Maintenance of Office or Agency.......................................42
              SECTION 10.03.        Money for Security Payments to be Held in Trust.......................42
              SECTION 10.04.        Limitation on Liens and Sale-Leasebacks...............................43
              SECTION 10.05.        Dividends on and Acquisitions of Stock................................45
              SECTION 10.06.        Waiver of Certain Covenants...........................................46
ARTICLE ELEVEN - REDEMPTION OF SECURITIES.................................................................46
              SECTION 11.01.        Applicability of Article..............................................46
              SECTION 11.02.        Election to Redeem; Notice to Trustee.................................47
              SECTION 11.03.        Selection by Trustee of Securities to Be Redeemed.....................47
              SECTION 11.04.        Notice of Redemption..................................................47
              SECTION 11.05.        Deposit of Redemption Price...........................................48
              SECTION 11.06.        Securities Payable on Redemption Date.................................48
              SECTION 11.07.        Securities Redeemed in Part...........................................48
ARTICLE TWELVE - SINKING FUNDS      49
              SECTION 12.01.        Applicability of Article..............................................49
              SECTION 12.02.        Satisfaction of Sinking Fund Payments With Securities.................49
              SECTION 12.03.        Redemption of Securities for Sinking Fund.............................49
</TABLE>


                                     -iii-
<PAGE>   7



                                    INDENTURE

         INDENTURE, dated as of January 1, 1992, between EL PASO NATURAL GAS
COMPANY, a Delaware corporation (herein called the "Company") with its principal
office at One Paul Kayser Center, 304 Texas Avenue, El Paso, Texas 79901, and
CITIBANK, N.A., a national banking association duly incorporated and existing
under the laws of the United States of America, as Trustee (herein called the
"Trustee").

                             RECITALS OF THE COMPANY

         The Company has duly authorized the execution and delivery of this
Indenture to provide for the issuance from time to time of its unsecured
debentures, notes or other evidences of indebtedness (herein called the
"Securities") to be issued in one or more series as provided in this Indenture.

         All things necessary to make this Indenture a valid agreement of the
Company and the Trustee, in accordance with its terms, have been done.

         NOW, THEREFORE, THIS INDENTURE WITNESSETH:

         That in order to declare the terms and conditions upon which the
Securities are made, executed, authenticated, issued and delivered, the Company
and the Trustee covenant and agree with each other, for the equal and
proportionate benefit of all Holders (as defined below) of the securities or of
any series thereof, as follows:


      ARTICLE ONE - DEFINITIONS AND OTHER PROVISIONS OF GENERAL APPLICATION

SECTION 1.01. DEFINITIONS

         For all purposes of this Indenture and any indenture supplemental
hereto, except as otherwise expressly provided or unless the context otherwise
requires:

         (1) the terms defined in this Article One have the meanings assigned to
them in this Article One and include the plural as well as the singular;

        (2) all accounting terms not otherwise defined herein have the meanings
assigned to them in accordance with generally accepted accounting principles,
and, except as otherwise herein expressly provided, the term "generally accepted
accounting principles" with respect to any computation required or permitted
hereunder shall mean such accounting principles as are generally accepted at the
date of this Indenture; and


<PAGE>   8

         (3) the words "herein," "hereof" and "hereunder" and other words of
similar import refer to this Indenture as a whole and not to any particular
Article, Section or other subdivision. Certain terms, used principally in
Article Six, are defined in Section 1.02.

         "Act" when used with respect to any Holder has the meaning specified in
Section 1.05.

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

         "Authorized Newspaper" means a newspaper of general circulation in the
New York, New York area, printed in the English language and customarily
published on each Business Day, whether or not published on Saturdays, Sundays
or holidays. Whenever successive weekly publications in an Authorized Newspaper
are required hereunder they may be made (unless otherwise expressly provided
herein) on the same or different days of the week and in the same or in
different Authorized Newspapers.

         "Board of Directors" means either the board of directors of the Company
or any duly authorized committee of that board.

         "Board Resolution" means a copy of a resolution certified by the
Secretary or an Assistant Secretary of the Company to have been duly adopted by
the Board of Directors and to be in full force and effect on the date of such
certification, and delivered to the Trustee.

         "Business Day" means each Monday, Tuesday, Wednesday, Thursday and
Friday which is not a day on which banking institutions in the State of New York
are authorized or obligated by law or executive order to close.

         "Commission" means the Securities and Exchange Commission, as from time
to time constituted, created under the Securities Exchange Act of 1934, or, if
at any time after the execution of this instrument such Commission is not
existing and performing the duties now assigned to it under the Trust Indenture
Act, then the body performing such duties at such time.

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

         "Company Request" or "Company Order" means a written request or order
signed in the name of the Company by its Chairman of the Board, its President, a
Vice Chairman or a Vice President, and by its Treasurer, an Assistant Treasurer,
its Secretary or an Assistant Secretary, and delivered to the Trustee.


                                      -2-
<PAGE>   9

         "Corporate Trust Office" means the principal office of the Trustee at
which at any particular time its corporate trust business shall be principally
administered, which office is, at the date as of which this Indenture is dated,
located at 120 Wall Street, New York, New York 10043 except that, with respect
to presentation of Securities for payment or registration of transfer and
exchange and the location of the Securities Registrar, such term means the
office or agency of the Trustee in said city at which, at any particular time,
its corporate agency business shall be conducted, which is, at the date as of
which this Indenture is dated, located at 111 Wall Street, New York, New York
10043.

         "Corporation" includes corporations, associations, companies and
business trusts.

         "Debt" means indebtedness for money borrowed.

         "Defaulted Interest" has the meaning specified in section 3.07.

         "Event of Default" has the meaning specified in Section 5.01.

         "Funded Debt" means all Debt maturing one year or more from the date of
the creation thereof, all Debt directly or indirectly renewable or extendible,
at the option of the debtor, by its terms or by the terms of any instrument or
agreement relating thereto, to a date one year or more from the date of the
creation thereof, and all Debt under a revolving credit or similar agreement
obligating the lender or lenders to extend credit over a period of one year or
more.

         "Holder" means a Person in whose name a Security is registered in the
Securities Register.

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

         "Interest Payment Date" means the Stated Maturity of an installment of
interest on the Securities.

         "Maturity," when used with respect to one of the Securities, means the
date on which the principal of such Security becomes due and payable as therein
or herein provided, whether at the Stated Maturity or by declaration of
acceleration or otherwise.

         "Mortgage" means and includes any mortgage, pledge, lien, charge,
security interest, conditional sale or other title retention agreement or other
similar encumbrance.

         "Officers' Certificate" means a certificate signed by the Chairman of
the Board, the President, a Vice Chairman or a Vice President, and by the
Treasurer, an Assistant Treasurer, the Secretary or an Assistant Secretary, of
the Company, and delivered to the Trustee, which shall to the extent applicable
contain the statements required by Section 1.03.



                                       -3-
<PAGE>   10

         "Opinion of Counsel" means a written opinion of counsel, who may be
counsel for the Company, and who shall be acceptable to the Trustee, which shall
to the extent applicable contain the statements required by Section 1.03.

         "Outstanding," when used with respect to Securities, means, as of the
date of determination, all Securities theretofore authenticated and delivered
under this Indenture, except:

                  (i)  Securities theretofore cancelled by the Trustee or 
         delivered to the Trustee for cancellation;

                  (ii) Securities, or portions thereof, for whose payment money
         in the necessary amount has been theretofore deposited with the Trustee
         or any Paying Agent (other than the Company) in trust or set aside and
         segregated in trust by the Company (if the Company shall act as its own
         Paying Agent) for the Holders of such Securities; and

                  (iii) Securities in exchange for or in lieu of which other
         Securities have been authenticated and delivered pursuant to this
         Indenture;

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

         "Paying Agent" means any Person authorized by the Company to pay the
principal of or interest on any Securities on behalf of the Company.

         "Person" means any individual, corporation, partnership, joint venture,
association, joint-stock company, trust, unincorporated organization or
government or any agency or political subdivision thereof.

         "Predecessor Security" of any particular Security means every previous
Security evidencing all or a portion of the same debt as that evidenced by such
particular Security; and, for the purposes of this definition, any Security
authenticated and delivered under Section 3.06 in exchange for or in lieu of a
mutilated, destroyed, lost or stolen Security shall be deemed to evidence the
same debt as the mutilated, destroyed, lost or stolen Security.

         "Principal Property" means (i) any pipeline assets of the Company or
any Subsidiary, including any related facilities employed in the transportation,
distribution or marketing of 




                                       4-
<PAGE>   11

natural gas, and (ii) any processing plant owned or leased by the Company or any
Subsidiary and located within the United States of America or any state thereof
or the Dominion of Canada or any province or territory thereof, except any such
assets or plant which in the opinion of the Board of Directors are not Principal
Properties in relation to the activities of the Company and its Subsidiaries as
a whole.

         "Record Date" for the interest payable on any Interest Payment Date
means the date specified pursuant to Section 3.01.

         "Redemption Date," when used with respect to any Security to be
redeemed, means the date fixed for such redemption by or pursuant to this
Indenture.

         "Redemption Price," when used with respect to any Security to be
redeemed, means the price at which it is to be redeemed by or pursuant to this
Indenture.

         "Responsible Officer," when used with respect to the Trustee, means the
chairman or any vice-chairman of the board of directors, the chairman or any
vice-chairman of the executive committee of the board of directors, the chairman
of the trust committee, the president, any vice president, the secretary, any
assistant secretary, the treasurer, any assistant treasurer, the cashier, any
assistant cashier, any trust officer or assistant trust officer, the controller
or any assistant controller or any other officer of the Trustee customarily
performing functions similar to those performed by any of the above designated
officers and also means, with respect to a particular corporate trust matter,
any other officer to whom such matter is referred because of his knowledge of
and familiarity with the particular subject.

         "Securities" has the meaning stated in the first recital of this
Indenture and more particularly means any securities authenticated and delivered
under this Indenture.

         "Securities Register" and "Securities Registrar" have the respective
meanings specified in Section 3.05.

         "Special Record Date" for the payment of any Defaulted Interest means a
date fixed by the Trustee pursuant to Section 3.07.

         "Stated Maturity," when used with respect to any Security or any
installment of interest thereon, means the date specified in such Security as
the fixed date on which the principal of such Security or such installment of
interest is due and payable.

         "Subsidiary" means a corporation more than 50% of the outstanding
Voting Stock 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.

         "Trustee" means the person named as the "Trustee" in the first
paragraph of this instrument until a successor Trustee shall have become such
pursuant to the applicable provisions of this Indenture, and thereafter
"Trustee" shall mean such successor Trustee.



                                      -5-
<PAGE>   12

         "Trust Indenture Act" means the Trust Indenture Act of 1939, as
amended, as in force at the date as of which this instrument was executed,
except as provided in Section 9.05.

         "Vice President," when used with respect to the Company or the Trustee,
means any vice president, whether or not designated by a number or a word or
words added before or after the title "vice president."

         "Voting Stock" means stock which ordinarily has voting power for the
election of a majority of directors, whether at all times or only so long as no
senior class of stock has such voting power by reason of any contingency.

SECTION 1.02. INCORPORATION BY REFERENCE OF TRUST INDENTURE ACT

         Whenever this Indenture refers to a provision of the Trust Indenture
Act, the provision is incorporated by reference in and made a part of this
Indenture. The following Trust Indenture Act terms used in this Indenture have
the following meanings:

         "Bankruptcy Act" means the Bankruptcy Act (Title 11 of the United
States Code).

         "indenture securities" means the Securities.

         "indenture security holder" means a Holder.

         "indenture to be qualified" means this Indenture.

         "indenture trustee" or "institutional trustee" means the Trustee.

         "obligor" on the Securities means the Company or any other obligor on
the Securities.

         All the other Trust Indenture Act terms used in this Indenture that are
defined by the Trust Indenture Act, defined by Trust Indenture Act. Reference to
another statute or defined by Commission rule have the meanings assigned to them
thereby.

SECTION 1.03. COMPLIANCE CERTIFICATES AND OPINIONS

         Upon any application or request by the Company to the Trustee to take
any action under any provision of this Indenture, the Company shall furnish to
the Trustee an Officers, Certificate stating that all conditions precedent, if
any, provided for in this Indenture relating to the proposed action have been
complied with and an Opinion of Counsel stating that in the opinion of such
counsel all such conditions precedent, if any, have been complied with, except
that in the case of any such application or request as to which the furnishing
of such documents is specifically required by any provision of this Indenture
relating to such particular application or request, no additional certificate or
opinion need be furnished.



                                      -6-
<PAGE>   13

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

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

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

         (3) a statement that, in the opinion of each such individual, he has
made such examination or investigation as is necessary to enable him to express
an informed opinion as to whether such covenant or condition has been complied
with; and

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

SECTION 1.04. FORM OF DOCUMENTS DELIVERED TO TRUSTEE

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

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

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

SECTION 1.05. ACTS OF HOLDERS

         (a) Any request, demand, authorization, direction, notice, consent,
waiver or other action provided by this Indenture to be given or taken by
Holders of the Outstanding Securities of all series or one or more series, as
the case may be, may be embodied in and evidenced by one or more instruments of
substantially similar tenor signed by such Holders in person or by an 


                                      -7-
<PAGE>   14

agent duly appointed in writing; and, except as herein otherwise expressly
provided, such action shall become effective when such instrument or instruments
are delivered to the Trustee and, where it is hereby expressly required, to the
Company. Such instrument or instruments (and the action embodied therein and
evidenced thereby) are herein sometimes referred to as the "Act" of the Holder
or Holders signing such instrument or instruments. Proof of execution of any
such instrument or of a writing appointing any such agent shall be sufficient
for any purpose of this Indenture and (subject to Section 6.01) conclusive in
favor of the Trustee and the Company, if made in the manner provided in this
Section 1.05. The Company may set a record date for purposes of determining the
identity of Holders entitled to vote or consent to any action by vote or consent
authorized or permitted under this Indenture, which record date shall be not
earlier than 30 days prior to the first solicitation of such vote or consent. If
a record date is fixed, those persons who were Holders of Securities at such
record date (or their duly designated proxies), and only those persons, shall be
entitled to take such action by vote or consent or to revoke any vote or consent
previously given, whether or not such persons continue to be Holders after such
record date. No such vote or consent shall be valid or effective for more than
120 days after such record date.

         (b) The fact and date of the execution by any Person of any such
instrument or writing may be proved by the affidavit of a witness of such
execution or by a certificate of a notary public or other officer authorized by
law to take acknowledgments of deeds, certifying that the individual signing
such instrument or writing acknowledged to him the execution thereof. Where such
execution is by a signer acting in a capacity other than his individual
capacity, such certificate or affidavit shall also constitute sufficient proof
of his authority. The fact and date of the execution of any such instrument or
writing, or the authority of the person executing the same, may also be proved
in any other manner which the Trustee deems sufficient.

         (c) The ownership of Securities shall be proved by the Securities
Register.

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

SECTION 1.06. NOTICES, ETC., TO TRUSTEE AND COMPANY

         Any request, demand, authorization, direction, notice, consent, waiver
or Act of Holders or other document provided or permitted by this Indenture to
be made upon, given or furnished to, or filed with:

         (a) the Trustee by any Holder or by the Company shall be sufficient for
every purpose hereunder if made, given, furnished or filed in writing to or with
the Trustee at its Corporate Trust Office, Attention: Corporate Trust
Administration or



                                      -8-
<PAGE>   15

         (b) the Company by the Trustee or by any Holder shall be sufficient for
every purpose hereunder (unless otherwise herein expressly provided) if in
writing and mailed, first-class postage prepaid, to the Company addressed to it
at the address of its principal office specified in the first paragraph of this
Indenture or at any other address previously furnished in writing to the Trustee
by the Company, Attention: Senior Vice President and Chief Financial Officer.

SECTION 1.07. NOTICES TO HOLDERS; WAIVER

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

         In case by reason of the suspension of regular mail service, or by
reason of any other cause, it shall be impracticable to give notice as required
by this Indenture, then such method of notification as shall be made with the
approval of the Trustee shall constitute a sufficient notice.

SECTION 1.08. CONFLICT WITH TRUST INDENTURE ACT

         If any provision hereof limits, qualifies or conflicts with another
provision hereof which is required to be included in this Indenture by any of
the provisions of the Trust Indenture Act, such required provision shall
control. If any provision of this Indenture modifies or excludes any provision
of the Trust Indenture Act that may be so modified or excluded, the latter
provision shall be deemed to apply to this Indenture as so modified or to be
excluded, as the case may be.

SECTION 1.09. EFFECT OF READINGS AND TABLE OF CONTENTS

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

SECTION 1.10. SUCCESSORS AND ASSIGNS

All covenants and agreements in this Indenture by the Company shall bind its
successors and assigns, whether so expressed or not.





                                      -9-
<PAGE>   16

SECTION 1.11. SEPARABILITY CLAUSE

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

SECTION 1.12. BENEFITS OF INDENTURE

         Nothing in this Indenture or in the Securities, express or implied,
shall give to any Person, other than the parties hereto and their successors
hereunder and the Holders of Securities, any benefit or any legal or equitable
right, remedy or claim under this Indenture.

SECTION 1.13. GOVERNING LAW

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

SECTION 1.14. LEGAL HOLIDAYS

         In any case where any Interest Payment Date, Redemption Date or Stated
Maturity of any Security shall not be a Business Day, then (notwithstanding any
other provision of this Indenture or of the Securities) payment of interest on
or principal (and premium, if any) of such Security need not be made on such
date, but may be made on the next succeeding Business Day with the same force
and effect as if made on the Interest Payment Date, Redemption Date or at the
Stated Maturity; and if so made, no interest shall accrue for the period from
and after such Interest Payment Date, Redemption Date or Stated Maturity, as the
case may be.


                        ARTICLE TWO - FORM OF SECURITIES

SECTION 2.01. FORMS GENERALLY

         The Securities of each series and the Trustee's certificates of
authentication shall be in substantially such form (not inconsistent with this
Indenture) as shall be established by or pursuant to one or more Board
Resolutions and set forth in such Board Resolutions, or, to the extent
established pursuant to, rather than set forth in, such Board Resolutions, an
officers' Certificate detailing such establishment, or in one or more indentures
supplemental hereto, in each case with such appropriate insertions, omissions,
substitutions and other variations as are required or permitted by this
Indenture and may have imprinted or otherwise reproduced thereon such letters,
numbers or other marks of identification and such legends or endorsements placed
thereon, not inconsistent with the provisions of this Indenture, as may be
required to comply with any law or with any rules or regulations pursuant
thereto, or with any rules of any securities exchange or to conform to general
usage, all as determined by the Officers executing such Securities, as evidenced
by such execution. If the form or forms of Securities of any series are
established by action taken pursuant to a Board Resolution of the Company, a
copy of an 



                                      -10-
<PAGE>   17

appropriate record of such action shall be certified by the Secretary or an
Assistant Secretary of the Company and delivered to the Trustee at or prior to
the delivery of the Company order contemplated by Section 3.03 for the
authentication and delivery of such Securities.

         The definitive Securities shall be printed, lithographed or engraved or
produced by any combination of these methods on steel engraved borders or may be
produced in any other manner permitted by the rules of any securities exchange
on which the Securities may be listed, all as determined by the officers
executing such Securities, as evidenced by their execution of such Securities.

SECTION 2.02. FORM OF TRUSTEE'S CERTIFICATE OF AUTHENTICATION

         The Trustee's certificate of authentication on all Securities shall be
in substantially the following form:

         This is one of the Securities of the series designated herein and
referred to in the within-mentioned Indenture.

CITIBANK, N.A.
as Trustee



By: __________________
Authorized Signatory


                         ARTICLE THREE - THE SECURITIES

SECTION 3.01. TITLE AND TERMS

         The aggregate principal amount of Securities which may be authenticated
and delivered under this Indenture is not limited.

         The Securities may be issued in one or more series. There shall be
established in or pursuant to Board Resolutions and set forth in an Officers'
Certificate, or established in one or more indentures supplemental hereto, prior
to the issuance of Securities of any series, any or all of the following as
applicable:

                  (1) the title of the Securities of the series (which shall
         distinguish the Securities of the series from all other series of
         Securities);

                  (2) any limit upon the aggregate principal amount of the
         Securities of the series that may be authenticated and delivered under
         this Indenture (except for Securities 


                                      -11-
<PAGE>   18

         authenticated and delivered upon registration of transfer of, or in
         exchange for, or in lieu of, other Securities of the series pursuant
         to Section 3.04, 3.05, 3.06, 9.06 or 11.07);

                  (3) the date or dates on which the principal of the Securities
         of the series is payable or the manner in which such dates are
         determined;

                  (4) the rate or rates at which the Securities of the series
         shall bear interest, or the manner in which such rates are to be
         determined, the date or dates from which such interest shall accrue, or
         the manner in which such dates are to be determined, the Interest
         Payment Dates on which such interest shall be payable and the Record
         Dates, if any, for the interest payable on any Interest Payment Date;

                  (5) the place or places where the principal of (and premium,
         if any, on) and interest, if any, on Securities of the series shall be
         payable;

                  (6) the period or periods within which, the date or dates on
         which, the price or prices at which and the terms and conditions upon
         which Securities of the series may be redeemed, in whole or in part, at
         the option of the Company;

                 (7) the obligation, if any, of the Company to redeem, purchase
        or repay Securities of the series pursuant to any sinking fund,
        amortization or other provisions and the period or periods within which
        or the date or dates on which, the price or prices at which and the
        terms and conditions upon which Securities of the series shall be
        redeemed, purchased or repaid, in whole or in part, pursuant to such
        obligation;

                 (8) if other than denominations of $1,000 and any integral
        multiple thereof, the denominations in which Securities of the series
        shall be issuable;

                 (9) if other than the Trustee, the identity of the Securities
        Registrar and/or the Paying Agent;

                 (10) if other than the principal amount thereof, the portion of
        the principal amount of Securities of the series which shall be payable
        upon declaration of acceleration of the Maturity thereof pursuant to
        Section 5.02;

                 (11) if other than such coin or currency of the United States
        of America as at the time of payment is legal tender for payment of
        public or private debts, the coin or currency or currency unit in which
        payment of the principal of (and premium, if any, on) or interest, if
        any, on the Securities of the series shall be payable;

                 (12) if the amount of payment of principal of (and premium, if
        any, on) or interest, if any, on the Securities of the series may be
        determined with reference to an index, formula or other method based on
        a coin or currency or currency unit other than that in which the
        Securities are stated to be payable, the manner in which such amounts
        shall be determined;


                                      -12-
<PAGE>   19

                 (13) if the principal of (and premium, if any, on) or interest,
        if any, on the Securities of the series are to be payable, at the
        election of the Company or a Holder thereof, in a coin or currency or
        currency unit other than that in which the Securities are stated to be
        payable, the period or periods within which, or the date or dates on
        which and the terms and conditions upon which, such election may be
        made;

                  (14) whether the Securities of the series are subject to
         defeasance or covenant defeasance, or such other means of satisfaction
         and discharge as may be specified for a series;

                 (15) any deletions or modifications of or additions to the
        Events of Default set forth in Section 5.01 or covenants of the Company
        set forth in Article Eight or Ten pertaining to the Securities of the
        series;

                  (16) the forms of the Securities of any series; and

                  (17) any other terms, conditions, rights and preferences (or
         limitations on such rights and preferences) relating to the series
         (which terms shall not be inconsistent with the provisions of this
         Indenture).

         Not all Securities of any one series need be issued at the same time,
and, unless otherwise provided, a series may be reopened for issuances of
additional Securities of such series.

         If any of the terms of the series are established by action taken
pursuant to a Board Resolution, such Board Resolution and the officers,
Certificate setting forth the terms of the series shall be delivered to the
Trustee at or prior to the delivery of the Company order for authentication and
delivery of Securities of such series.

         The principal of (and premium, if any, on) and interest on the
Securities shall be payable at the office or agency of the Company in the
Borough of Manhattan, The City of New York, maintained for such purpose and at
any other office or agency maintained by the Company for such purpose; provided,
however, that interest may be payable at the option of the Company by check
mailed to the address of the person entitled thereto as such address shall
appear on the Securities Register.

SECTION 3.02. DENOMINATIONS

         The Securities of each series shall be issuable in definitive
registered form without coupons and in such denominations as shall be specified
as contemplated by Section 3.01. In the absence of any such provision with
respect to the Securities of any series, the Securities of such series shall be
issuable in denominations of $1,000 and any integral multiple thereof.



                                      -13-
<PAGE>   20

SECTION 3.03. EXECUTION, AUTHENTICATION, DELIVERY AND DATING

         The Securities shall be executed on behalf of the company by its
Chairman of the Board, its President, a Vice Chairman or one of its Vice
Presidents, under its corporate seal reproduced thereon attested by its
Secretary or one of its Assistant Secretaries. The signature of any of these
officers on the Securities may be manual or facsimile.

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

         At any time and from time to time after the execution and delivery of
this Indenture, the Company may deliver Securities of any series executed by the
Company to the Trustee for authentication, together with a Company Order for the
authentication and delivery of such Securities; and the Trustee in accordance
with such Company Order shall authenticate and deliver such Securities as in
this Indenture provided and not otherwise. If not all the Securities of any
series are to be issued at one time and if the Board Resolution or supplemental
indenture establishing such series shall so permit, such Company Order may set
forth procedures acceptable to the Trustee for the issuance of such securities
and the determination of the terms of particular Securities of such series such
as interest rate, Stated Maturity, date of issuance and date from which interest
shall accrue. In authenticating such Securities, and accepting the additional
responsibilities under this Indenture in relation to such Securities, the
Trustee shall be entitled to receive, and shall be fully protected in relying
upon, an opinion of Counsel stating:

                   (a) that the form or forms and terms of such Securities have
          been established in conformity with the provisions of this Indenture
          and

                   (b) that such Securities, when completed by appropriate
          insertions and executed by the Company and delivered to the Trustee
          for authentication in accordance with this Indenture, authenticated
          and delivered by the Trustee in accordance with this Indenture and
          issued by the company in the manner and subject to any conditions
          specified in such Opinion of Counsel, will constitute the legal, valid
          and binding obligations of the Company.

          If not all the Securities of any series are to be issued at one time,
it shall not be necessary to deliver an Opinion of Counsel at the time of
issuance of each Security, but such opinion with appropriate modifications
shall be delivered at or before the time of issuance of the first Security of
such series. The Trustee shall not be required to authenticate Securities if
the issuance of such Securities pursuant to this Indenture will affect the
Trustee's own rights, duties or immunities under the Securities and this
Indenture or otherwise in a manner which is not reasonably acceptable to the
Trustee.

          Each Security shall be dated the date of its authentication.



                                      -14-
<PAGE>   21

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

SECTION 3.04. TEMPORARY SECURITIES

         Pending the preparation of definitive Securities of any series, the
Company may execute, and upon Company order the Trustee shall authenticate and
deliver, temporary Securities which are printed, lithographed, typewritten,
mimeographed or otherwise produced, in any authorized denomination,
substantially of the tenor of the definitive Securities in lieu of which they
are issued, with such appropriate insertions, omissions, substitutions and other
variations as the officers executing such Securities may determine, as evidenced
by their execution of such Securities.

         If temporary Securities of any series are issued, the Company will
cause definitive Securities of each such series to be prepared without
unreasonable delay. After the preparation of definitive Securities of any
series, the temporary Securities of each such series shall be exchangeable for
definitive Securities upon surrender of the temporary Securities of such series
at any office or agency of the Company designated pursuant to Section 10.02,
without charge to the Holder. Upon surrender for cancellation of any one or more
temporary Securities of any series the Company shall execute and the Trustee
shall authenticate and deliver in exchange therefor a like principal amount of
definitive Securities of authorized denominations of the same series. Until so
exchanged the temporary Securities of any series shall in all respects be
entitled to the same benefits under this Indenture as definitive Securities of
such series.

SECTION 3.05. REGISTRATION, REGISTRATION OF TRANSFER AND EXCHANGE

         The Company shall cause to be kept at the Corporate Trust Office of the
Trustee a register (the register maintained in such office and in any other
office or agency designated pursuant to Section 10.02 being herein sometimes
collectively referred to as the "Securities Register") in which, subject to such
reasonable regulations as it may prescribe, the Company shall provide for the
registration of Securities and of transfers of Securities. The Trustee is hereby
appointed "Securities Registrar" for the purposes of registration and transfer
of Securities as herein provided.

         Upon surrender for registration of transfer of any Securities of a
series at an office or agency of the Company designated pursuant to Section
10.02 for such purpose, the Company shall execute, and the Trustee shall
authenticate and deliver, in the name of the designated transferee or
transferees, one or more new Securities of the same series of any authorized
denominations, of a like aggregate principal amount.

         At the option of the Holder, Securities of a series may be exchanged
for other Securities of the same series, of any authorized denominations, of a
like aggregate principal amount, upon 



                                      -15-
<PAGE>   22

surrender of the Securities of such series to be exchanged at such office or
agency, and upon payment, if the Company shall so require, of the charges
hereinafter provided. Whenever any Securities are so surrendered for exchange,
the Company shall execute, and the Trustee shall authenticate and deliver, the
securities which the Holder making the exchange is entitled to receive.

         All Securities issued upon any registration of transfer or exchange of
Securities shall be the valid obligations of the Company, evidencing the same
debt, and entitled to the same benefits under this Indenture, as the Securities
surrendered upon such registration of transfer or exchange.

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

         No service charge shall be made for any registration of transfer or
exchange of Securities, but the Company may require payment of a sum sufficient
to cover any tax or other governmental charge that may be imposed in connection
with any registration of transfer or exchange of Securities, other than
exchanges pursuant to Section 3.04 or 9.06 not involving any transfer.

         The Company shall not be required to (i) issue, register the transfer
of or exchange Securities of any series during a period beginning at the opening
of business 15 days before the day of the selection for redemption of Securities
of that series under Section 11.03 and ending at the close of business on the
day of the mailing of notice of redemption or (ii) register the transfer of or
exchange any Security so selected for redemption in whole or in part, except the
unredeemed portion of any Security being redeemed in part.

SECTION 3.06. MUTILATED, DESTROYED, LOST AND STOLEN SECURITIES

         If any mutilated Security is surrendered to the Trustee, the Company
shall execute and the Trustee shall authenticate and deliver in exchange
therefor a new Security of like series, tenor and principal amount and bearing a
number not contemporaneously outstanding.

         If there shall be delivered to the Company and the Trustee (i) evidence
to their satisfaction of the destruction, loss or theft of any Security and (ii)
such security or indemnity as may be required by them to save each of them and
any agent of either of them harmless, then, in the absence of notice to the
Company or the Trustee that such Security has been acquired by a bona fide
purchaser, the Company shall execute and upon its request the Trustee shall
authenticate and deliver, in lieu of any such destroyed, lost or stolen
Security, a new Security of like series, tenor and principal amount and bearing
a number not contemporaneously outstanding.

          In case any such mutilated, destroyed, lost or stolen Security has
become or is about to become due and payable, the Company in its discretion may,
instead of issuing a new Security, pay such Security.



                                      -16-
<PAGE>   23

          Upon the issuance of any new Security under this Section 3.06, the
Company may require the payment of a sum sufficient to cover any tax or other
governmental charge that may be imposed in relation thereto and any other
expenses (including the fees and expenses of the Trustee) connected therewith.

          Every new Security issued pursuant to this Section 3.06 in lieu of any
destroyed, lost or stolen Security shall constitute an original additional
contractual obligation of the Company, whether or not the destroyed, lost or
stolen Security shall be at any time enforceable by anyone, and shall be
entitled to all the benefits of this Indenture equally and proportionately with
any and all other Securities duly issued hereunder.

          The provisions of this Section 3.06 are exclusive and shall preclude
(to the extent lawful) all other rights and remedies with respect to the
replacement or payment of mutilated, destroyed, lost or stolen Securities.

SECTION 3.07. PAYMENT OF INTEREST; INTEREST RIGHTS PRESERVED

          Interest on any Security which is payable, and is punctually paid or
duly provided for, on any Interest Payment Date or within five days thereafter
shall be paid to the Person in whose name such Security (or one or more
Predecessor Securities) is registered at the close of business on the Record
Date for such interest; provided, however, that each installment of interest on
any Security may at the Company's option be paid by mailing a check for such
interest, payable to or upon the written order of the Person entitled thereto
pursuant to Section 3.08, to the address of such Person as it appears on the
Securities Register.

          Any interest on any Security which is payable, but is not punctually
paid or duly provided for, on any Interest Payment Date or within five days
thereafter (herein called "Defaulted Interest") shall forthwith cease to be
payable to the registered Holder on the relevant Record Date; and, except as
hereinafter provided, such Defaulted Interest may be paid by the Company, at its
election in each case, as provided in clause (1) or (2) below:

                   (1) The Company may elect to make payment of any Defaulted
          Interest to the Persons in whose names the Securities (or their
          respective Predecessor Securities) are registered at the close of
          business on a Special Record Date for the payment of such Defaulted
          Interest, which shall be fixed in the following manner. The Company
          shall notify the Trustee in writing of the amount of Defaulted
          Interest proposed to be paid on each Security and the date of the
          proposed payment, and at the same time the Company shall deposit with
          the Trustee an amount of money equal to the aggregate amount proposed
          to be paid in respect of such Defaulted Interest or shall make
          arrangements satisfactory to the Trustee for such deposit prior to the
          date of the proposed payment, such money when deposited to be held in
          trust for the benefit of the Persons entitled to such Defaulted
          Interest as in this Clause provided. Thereupon the Trustee shall fix a
          Special Record Date for the payment of such Defaulted interest which
          shall be not more than 15 and not less than 10 days prior to the date
          of the proposed payment and not less 



                                      -17-
<PAGE>   24

         than 10 days after the receipt by the Trustee of the notice of the
         proposed payment. The Trustee shall promptly notify the Company of
         such Special Record Date, and, in the name and at the expense of the
         Company, shall cause notice of the proposed payment of such Defaulted
         Interest and the Special Record Date therefor to be mailed, first
         class postage prepaid, to each Holder at his address as it appears in
         the Securities Register not less than 10 days prior to such Special
         Record Date. The Trustee may, in its discretion, in the name and at
         the expense of the Company, cause a similar notice to be published at
         least once in an Authorized Newspaper in the Borough of Manhattan, The
         City of New York, but such publication shall not be a condition
         precedent to the establishment of such Special Record Date. Notice of
         the proposed payment of such Defaulted Interest and the Special Record
         Date therefor having been mailed as aforesaid, such Defaulted Interest
         shall be paid to the Persons in whose names the Securities (or their
         respective Predecessor Securities), are registered on such Special
         Record Date and shall no longer be payable pursuant to the following
         Clause (2).

                  (2) The Company may make payment of any Defaulted Interest on
         the Securities of any series in any other lawful manner not
         inconsistent with the requirements of any securities exchange on which
         such Securities may be listed, and upon such notice as may be required
         by such exchange, if, after notice given by the Company to the Trustee
         of the proposed payment pursuant to this Clause, such payment shall be
         deemed practicable by the Trustee.

         Subject to the foregoing provisions of this Section 3.07, each Security
delivered under this Indenture upon transfer of or in exchange for or in lieu of
any other Security shall carry the rights to interest accrued and unpaid, and to
accrue, which were carried by such other Security.

SECTION 3.08. PERSONS DEEMED OWNERS

         Prior to due presentment of a Security for registration of transfer,
the Company, the Trustee and any agent of the Company or the Trustee may treat
the Person in whose name such Security is registered as the owner of such
Security for the purpose of receiving payment of principal of (and premium, if
any, on) and (subject to Section 3.07) interest, if any, on such Security and
for all other purposes whatsoever, whether or not such Security be overdue, and
neither the Company, the Trustee nor any agent of the Company or the Trustee
shall be affected by notice to the contrary.

SECTION 3.09. CANCELLATION

         All securities surrendered for payment, redemption, registration of
transfer or exchange or for credit against any sinking fund payment shall, if
surrendered to any Person other than the Trustee, be delivered to the Trustee
and shall be promptly cancelled by it. The Company may at any time deliver to
the Trustee for cancellation any Securities previously authenticated and
delivered hereunder which the Company may have acquired in any manner
whatsoever, and all Securities so delivered shall be promptly cancelled by the
Trustee. No Securities shall be authenticated in lieu of or in exchange for any
Securities cancelled as provided in this Section 



                                      -18-
<PAGE>   25

3.09, except as expressly permitted by this Indenture. All cancelled Securities
held by the Trustee shall be destroyed unless otherwise directed by a Company
Order.

SECTION 3.10. COMPUTATION OF INTEREST

         Except as otherwise specified as contemplated by Section 3.01 for
Securities of any series, any interest on the Securities of each series shall be
computed on the basis of a 360-day year of twelve 30-day months.


           ARTICLE FOUR - SATISFACTION AND DISCHARGE: UNCLAIMED MONEYS

SECTION 4.01. SATISFACTION AND DISCHARGE OF INDENTURE

          (A)      If at any time

                  (a) the Company shall have paid or caused to be paid the
principal of and interest on all the Securities of any series outstanding
hereunder, as and when the same shall have become due and payable, or

                  (b) the Company shall have delivered to the Trustee for
cancellation all Securities of any series theretofore authenticated (other than
any Securities which shall have been destroyed, lost or stolen and which shall
have been replaced or paid as provided in Section 3.06), or

                  (c) (i) all the Securities of such series not theretofore
delivered to the Trustee for cancellation shall have become due and payable, are
by their terms to become due and payable within one year or are to be called for
redemption within one year under arrangements satisfactory to the Trustee for
the giving of notice of redemption; and (ii) the Company shall have irrevocably
deposited or caused to be irrevocably deposited with the Trustee (or an escrow
agent satisfactory to the Trustee) as trust funds the entire amount in cash
(other than moneys repaid by the Trustee or any paying agent to the Company in
accordance with Section 4.04) or direct noncallable obligations of, or
noncallable obligations guaranteed by, the United States of America or an agency
thereof for the payment of which guarantee or obligation the full faith and
credit of the United States is pledged ("U.S. Government Obligations"), maturing
as to principal and interest in such amounts and at such times without
consideration of any reinvestment of such principal and interest as will ensure
the availability of cash, or a combination of U.S. Government obligations and
cash, sufficient to pay at Stated Maturity all the Securities of such series not
theretofore delivered to the Trustee for cancellation, including principal (and
premium, if any) and interest due or to become due to such date of Stated
Maturity (including any mandatory sinking fund payments) or Redemption Date, as
the case may be, and if, in any such case, the Company shall also pay or cause
to be paid all other sums payable hereunder by the Company with respect to
Securities of such series, then this Indenture shall cease to be of further
effect with respect to Securities of such series (except as to (i) rights of
registration of transfer 



                                      -19-
<PAGE>   26

and exchange, (ii) substitution of apparently mutilated, defaced, destroyed,
lost or stolen Securities, (iii) rights of Holders to receive payments of
principal thereof and interest thereon, upon the original stated due dates
therefor(including any mandatory sinking fund payments or Redemption Date (but
not upon acceleration), (iv) the rights, obligations and immunities of the
Trustee hereunder, and (v) the rights of the Holders of Securities of such
series as beneficiaries hereof with respect to the property so deposited with
the Trustee payable to all or any of them), and the Trustee, on demand of the
Company accompanied by an officers' Certificate and an Opinion of Counsel, each
stating that all conditions precedent herein provided relating to the
satisfaction and discharge of this Indenture with respect to Securities of such
series have been complied with and at the cost and expense of the Company, shall
execute proper instruments acknowledging such satisfaction of and discharging of
this Indenture with respect to Securities of such series.

          The Company agrees to reimburse the Trustee for any costs or expenses
 thereafter reasonably and properly incurred and to compensate the Trustee for
 any services thereafter reasonably and properly rendered by the Trustee in
 connection with this Indenture or the Securities of such series.
 Notwithstanding the foregoing provisions of this Section 4.01(A), the Company's
 obligations in Section 6.07 shall survive.

          (B) In addition to the provisions of the next preceding paragraph, the
 Company may terminate its obligations under the Securities of any series and
 this Indenture, except those obligations referred to in the penultimate
 paragraph of this Section 4.01, if all Securities of such series previously
 authenticated and delivered (other than destroyed, lost or stolen Securities of
 such series which have been replaced or paid or Securities of such series for
 whose payment money or securities have theretofore been held in trust and
 thereafter repaid to the Company, as provided in Section 4.04) have been
 delivered to the Trustee for cancellation and the Company has paid all sums
 payable by it hereunder, or if the Company has irrevocably deposited or caused
 to be deposited with the Trustee (or an escrow agent satisfactory to the
 Trustee), under the terms of an irrevocable trust agreement in form and
 substance satisfactory to the Trustee, as trust funds in trust solely for the
 benefit of the Holders for that purpose, (i) money or (ii) U.S. Government
 obligations, or a combination thereof, maturing as to principal and interest in
 such amounts and at such times as are sufficient without consideration of any
 reinvestment of such principal or interest, to pay principal of and interest on
 the outstanding Securities of such series to maturity, provided that the
 Trustee shall have been irrevocably instructed to apply such money or the
 proceeds of such U.S. Government Obligations to the payment of said principal
 of and interest with respect to the outstanding Securities of such series.

         Such irrevocable trust agreement shall include, among other things,
provision for (1) payment of the principal of and interest on the Securities of
such series, when due, including any mandatory sinking fund payments (2) payment
of the fees and expenses of the Trustee, its agents and counsel incurred or to
be incurred in connection with carrying out such trust provisions, (3) rights of
registration, transfer, substitution and exchange of Securities of such series
in accordance with the terms stated in this Indenture, and (4) continuation of
the rights and obligations and immunities of the Trustee as against the Holders
as stated in this Indenture.




                                      -20-
<PAGE>   27

         Notwithstanding the first paragraph of this Section 4.01(B), the
Company's obligations in Sections 3.05, 3.06, 4.04, 4.05, 5.02, 6.07, 6.10,
10.01 and 10.02 shall survive until the Securities of such series are no longer
outstanding; provided, however, that the Company's obligations in Section 5.02
shall survive only with respect to an Event of Default defined in Section
5.01(2) or 5.01(3). Thereafter the Company's obligations in Sections 4.04, 4.05
and 6.07 shall survive.

         After any such irrevocable deposit, accompanied by an officers'
Certificate which shall state that the provisions of the first two paragraphs of
this Section 4.01(B) have been complied with, and upon delivery by the Company
to the Trustee of an opinion of independent legal counsel who shall be
acceptable to the Trustee, or, in lieu thereof, a favorable determination by the
Internal Revenue Service to the effect that Holders of the Securities of such
series will not recognize income, gain or loss for federal income tax purposes
as a result of such deposit and discharge and will be subject to federal income
tax on the same amount and in the same manner and at the same time as would have
been the case if such deposit and discharge had not occurred, then the Company
shall be discharged of its obligations under the Securities of such series and
this Indenture except for those surviving obligations specified above, and the
Trustee upon request shall acknowledge in writing such discharge. Prior to the
delivery of such acknowledgement, the Trustee may require the Company to deliver
to it an Officers, Certificate and opinion of Counsel, each stating that all
conditions precedent provided for relating to the deposit and discharge
contemplated by this provision have been complied with, and the opinion of
Counsel shall also state that such deposit does not violate applicable law.

SECTION 4.02. DEPOSITED MONEYS TO BE HELD IN TRUST BY TRUSTEE

         All moneys deposited with the Trustee pursuant to Section 4.01 shall be
held in trust and applied by it to the payment, either directly or through any
paying agent (including the Company if acting as its own paying agent), to the
Holders of the particular Securities of such series for the payment of which
such moneys have been deposited with the Trustee of all sums due and to become
due thereon for principal and interest.

SECTION 4.03. PAYING AGENT TO REPAY MONEYS HELD

         Upon the satisfaction and discharge of this Indenture with respect to
Securities of any series, all moneys then held by any paying agent of the
Securities of such series (other than the Trustee) shall, upon demand of the
Company, be repaid to it or paid to the Trustee, and thereupon such paying agent
shall be released from all further liability with respect to such moneys.

SECTION 4.04. RETURN OF UNCLAIMED MONEYS

         Any moneys deposited with or paid to the Trustee for payment of the
principal of or interest on Securities and not applied but remaining unclaimed
by the Holders of Securities of any series for two years after the date upon
which the principal of or interest on such Securities, as the case may be, shall
have become due and payable, shall be repaid to the Company by the Trustee on
written demand and all liability of the Trustee shall thereupon cease; and the
Holder 



                                      -21-
<PAGE>   28

of any of the Securities of any series shall thereafter look only to the Company
for any payment which such Holder may be entitled to collect.

SECTION 4.05. REINSTATEMENT

         If the Trustee is unable to apply any money or U.S. Government
Obligations in accordance with Section 4.01 by reason of any legal proceeding or
by reason of any order or judgment of any court or governmental authority
enjoining, restraining or otherwise prohibiting such application, the Company's
obligations under this Indenture with respect to Securities of any series and
the Securities of such series shall be revived and reinstated as though no
deposit had occurred pursuant to Section 4.01 until such time as the Trustee is
permitted to apply all such money or U.S. Government Obligations in accordance
with Section 4.01; provided, however, that if the Company has made any payment
of interest on or principal of any Securities of such series because of the
reinstatement of its obligations, the Company shall be subrogated to the rights
of the Holders of such Securities to receive such payment from the money or U.S.
Government Obligations held by the Trustee.


                             ARTICLE FIVE - REMEDIES

SECTION 5.01. EVENTS OF DEFAULT

         "Event of Default" with respect to Securities of any series, wherever
used herein, means any one of the following events which shall have occurred and
be continuing (whatever the reason for such Event of Default and whether it
shall be voluntary or involuntary or be effected by operation of law or pursuant
to any judgment, decree or order of any court or any order, rule or regulation
of any administrative or governmental body):

          (1) default in the payment of the principal of any Security of such
series as and when the same shall become due and payable, either at its Maturity
or otherwise; or

          (2) default in the payment of any installment of interest on any
Security of such series when it becomes due and payable, and the continuance of
such default for a period of 30 days; or

          (3) default in the payment of any sinking fund payment, when and as
due by the terms of the Security of that series; or

          (4) default in the performance, or breach, of any covenant or warranty
of the Company in this Indenture or the Securities in respect of the Securities
of such series (other than a covenant or warranty in respect of the Securities
of such series a default in whose performance or whose breach is elsewhere in
this Section specifically dealt with), and continuance of such default or breach
for a period of 60 days after there has been given, by registered or certified
mail, to the Company by the Trustee or to the Company and the Trustee by the
Holders of at least 25% in principal amount of the Outstanding Securities of all
series affected thereby, a 



                                      -22-
<PAGE>   29

written notice specifying such default or breach and requiring it to be remedied
and stating that such notice is a "Notice of Default" hereunder; or

          (5) a default under any bond, debenture, note or other evidence of
Debt of the Company or any Subsidiary (including any other series of Securities)
or under any mortgage, indenture or instrument under which there may be issued
or by which there may be secured or evidenced any Debt of the Company or any
Subsidiary, whether such Debt now exists or shall hereafter be created, which
default shall involve the failure to pay principal of, or interest on, Debt in
excess of $25,000,000 at the stated maturity thereof or shall have resulted in
Debt in excess of $25,000,000 becoming or being declared due and payable prior
to the date on which it would otherwise have become due and payable, without
such acceleration having been rescinded, stayed or annulled, or such Debt having
been discharged, within a period of 15 days after there shall have been given,
by registered or certified mail, to the Company by the Trustee or to the Company
and the Trustee by the Holders of at least 25% in principal amount of the
Outstanding Securities (or 25% of the Outstanding Securities of all series of
Securities not in default in case of a default with respect to one or more other
series of Securities) a written notice specifying such default and requiring the
Company to cause such acceleration to be rescinded or annulled or cause such
Debt to be discharged and stating that such notice is a "Notice of Default"
hereunder; or

         (6) the entry of a decree or order by a court having jurisdiction in
the premises adjudging the Company a bankrupt or insolvent, or approving as
properly filed a petition seeking relief, reorganization, arrangement,
adjustment or composition of or in respect of the Company under federal
bankruptcy law or any other applicable federal or state law, or appointing a
receiver, liquidator, assignee, trustee, sequestrator, custodian or other
similar official of the Company or of any substantial part of its property, or
ordering the winding up or liquidation of its affairs, and the continuance of
any such decree or order unstayed and in effect for a period of 60 consecutive
days; or

          (7) the institution by the Company of proceedings to be adjudicated a
bankrupt or insolvent, or the consent by it to the institution of bankruptcy or
insolvency proceedings against it, or the filing by it of a petition or answer
or consent seeking reorganization or relief under federal bankruptcy law or any
other applicable federal or state law, or the consent by it to the filing of
such petition or to the appointment of or taking of possession by a receiver,
liquidator, assignee, trustee, sequestrator, custodian or similar official of
the Company or of any substantial part of its property, or the making by it of a
general assignment for the benefit of creditors, or the failure of the Company
generally to pay its debts as they become due, or the taking of corporate action
by the Company in furtherance of any such action; or

          (8) any other Event of Default provided with respect to Securities of
that series.

SECTION 5.02. ACCELERATION OF MATURITY; RESCISSION AND ANNULMENT

          If an Event of Default described in Section 5.01(l), (2), (3), (4) (if
the Event of Default under clause (4) is with respect to less than all series of
Securities then outstanding) or (8) above 


                                      -23-
<PAGE>   30

occurs and is continuing, then and in every such case the Trustee or the Holders
of not less than 25% in principal amount of the Securities of such series then
Outstanding (each such series voting as a separate class) may declare the
principal of all the Securities of such series to be due and payable
immediately, by a notice in writing to the Company (and to the Trustee if given
by Holders), and upon any such declaration such principal shall become and shall
be immediately due and payable, anything in this Indenture or in the Security
contained to the contrary notwithstanding. Upon payment of such amount, all
obligations of the Company in respect of the payment of principal of the
Securities of such series shall terminate. If an Event of Default described in
Section 5.01(4) (if the Event of Default under clause (4) is with respect to all
series of Securities then outstanding), Section 5.01(5), (6) or (7) above occurs
and is continuing, then and in every such case, unless the principal of all the
Securities shall have already become due and payable, the Trustee or the Holders
of not less than 25% in principal amount of all the Securities then Outstanding
(treated as one class) which have not previously become due and payable may
declare the entire principal of all the Securities then outstanding to be due
and payable immediately, by notice in writing to the Company (and to the Trustee
if given by Holders) and upon any such declaration such principal shall become
and shall be immediately due and payable, anything in this Indenture or in the
Securities contained to the contrary notwithstanding. Upon payment of such
amount, all obligations of the Company in respect of the payment of principal of
the Securities shall terminate.

          At any time after such a declaration of acceleration has been made and
before a judgment or decree for payment of the money due has been obtained by
the Trustee as hereinafter in this Article provided, the Holders of a majority
in principal amount of the Outstanding Securities of each series so affected, by
written notice to the Company and the Trustee, may rescind and annul such
declaration and its consequences if

         (1) the Company has paid or deposited with the Trustee a sum sufficient
to pay

             (A) all overdue installments of interest on the Securities of such 
series, and

             (B) the principal of (and premium, if any, on) and any sinking
fund payments with respect to any Securities of such series which have become
due otherwise than by such declaration of acceleration, with interest thereon
from the date such principal became due at the rate borne by the Securities of
such series, and

             (C) to the extent that payment of such interest is lawful, interest
upon overdue installments of interest at the rate borne by the Securities of 
such series, and

             (D) all sums paid or advanced by the Trustee hereunder and the 
reasonable compensation, expenses, disbursements and advances of the Trustee, 
its agents and counsel; and

         (2) all Events of Default, other than the nonpayment of the principal
of Securities of such series which have become due solely by such declaration of
acceleration, have been cured or waived as provided in Section 5.13.




                                      -24-
<PAGE>   31

          No such rescission shall affect any subsequent default or impair any
right consequent thereon.

SECTION 5.03. COLLECTION OF INDEBTEDNESS AND SUITS FOR ENFORCEMENT BY TRUSTEE

         The Company covenants that if default is made in the payment of (1) any
installment of interest on any Security of any series when such interest becomes
due and payable and such default continues for a period of 30 days or (2) the
principal of (and premium, if any, on) any Security of any series at the
Maturity thereof or otherwise, the Company will, upon demand of the Trustee, pay
to the Trustee, for the benefit of the Holders of such Securities of each series
so affected, the whole amount then due and payable on such Securities of such
series for principal (and premium, if any) or interest, if any, or both, as the
case may be, with interest upon the overdue principal and, to the extent that
payment of such interest shall be legally enforceable, upon overdue installments
of interest, at the rate per annum borne by the Securities during the period of
such default; and, in addition thereto, such further amount as shall be
sufficient to cover the costs and expenses of collection, including the
reasonable compensation, expenses, disbursements and advances of the Trustee,
its agents and counsel.

          If the Company fails to pay such amounts forthwith upon such demand,
the Trustee, in its own name and as trustee of an express trust, may institute a
judicial proceeding for the collection of the sums so due and unpaid, may
prosecute such proceeding to judgment or final decree and may enforce the same
against the Company or any other obligor upon the Securities of each series so
affected and collect the moneys adjudged or decreed to be payable in the manner
provided by law out of the property of the Company or any other obligor upon the
Securities of each series so affected, wherever situated.

          If an Event of Default occurs and is continuing, the Trustee may in
its discretion proceed to protect and enforce its rights and the rights of the
Holders by such appropriate judicial proceedings as the Trustee shall deem most
effectual to protect and enforce any such rights, whether for the specific
enforcement of any covenant or agreement in this Indenture or in aid of the
exercise of any power granted herein, or to enforce any other proper remedy.

SECTION 5.04. TRUSTEE MAY FILE PROOFS OF CLAIM

          In case of the pendency of any receivership, insolvency, liquidation,
bankruptcy, reorganization, arrangement, adjustment, composition or other
judicial proceeding relative to the Company or any other obligor upon the
Securities or the property of the Company or of such other obligor or their
creditors, the Trustee (irrespective of whether the principal of the Securities
of each series so affected shall then be due and payable as therein expressed or
by declaration or otherwise and irrespective of whether the Trustee shall have
made any demand on the Company for the payment of overdue principal or interest)
shall be entitled and empowered, by intervention in such proceeding or
otherwise,

         (a) to file and prove a claim for the amount of principal (and premium,
if any) and interest, if any, owing and unpaid in respect of the Securities of
each series so affected and to 



                                      -25-
<PAGE>   32

file such other papers or documents as may be necessary or advisable in order to
have the claims of the Trustee (including any claim for the reasonable
compensation, expenses, disbursements and advances of the Trustee, its agents
and counsel) and of the Holders allowed in such judicial proceeding and

         (b) to collect and receive any moneys or other property payable or
deliverable on any such claims and to distribute the same;

and any receiver, assignee, trustee, liquidator, sequestrator, custodian or
other similar official in any such judicial proceeding is hereby authorized by
each Holder to make such payments to the Trustee and, in the event that the
Trustee shall consent to the making of such payments directly to the Holders, to
pay to the Trustee any amount due it for the reasonable compensation, expenses,
disbursements and advances of the Trustee, its agents and counsel, and any other
amounts due the Trustee under Section 6.07.

         Nothing herein contained shall be deemed to authorize the Trustee to
authorize or consent to or accept or adopt on behalf of any Holder any plan of
reorganization, arrangement, adjustment or composition affecting the Securities
or the rights of any Holder thereof or to authorize the Trustee to vote in
respect of the claim of any Holder in any such proceeding.

SECTION 5.05. TRUSTEE MAY ENFORCE CLAIMS WITHOUT POSSESSION OF SECURITIES

         All rights of action and claims under this Indenture or the Securities
may be prosecuted and enforced by the Trustee without the possession of any of
the Securities or the production thereof in any proceeding relating thereto, and
any such proceeding instituted by the Trustee shall be brought in its own name
as trustee of an express trust, and any recovery of judgment shall, after
provision for the payment of the reasonable compensation, expenses,
disbursements and advances of the Trustee, its agents and counsel, be for the
ratable benefit of the Holders of the Securities in respect of which such
judgment has been recovered.

SECTION 5.06. APPLICATION OF MONEY COLLECTED

         Any money collected by the Trustee pursuant to this Article Five shall
be applied in the following order, at the date or dates fixed by the Trustee
and, in case of the distribution of such money on account of principal (and
premium, if any) or interest, if any, upon presentation of the Securities and
the notation thereon of the payment if only partially paid and upon surrender
thereof if fully paid:

         FIRST: To the payment of all amounts due the Trustee under 
Section 6.07;

         SECOND: To the payment of the amounts then due and unpaid for principal
of (and premium, if any, on) and interest, if any, on the Securities of the
series in respect of which or for the benefit of which such money has been
collected, ratably, without preference or priority of any kind, according to the
amounts due and payable on such Securities for principal (and premium, if any)
and interest, if any, respectively; and




                                      -26-
<PAGE>   33

          THIRD: The balance, if any, to the Persons entitled thereto.

SECTION 5.07. LIMITATION ON SUITS

         No Holder of any Security of any series shall have any right to
institute any proceeding, judicial or otherwise, with respect to this Indenture,
or for the appointment of a receiver or trustee, or for any other remedy
hereunder, unless

         (a) such Holder has previously given written notice to the Trustee of a
continuing Event of Default with respect to the Securities of that series;

         (b) the Holders of not less than 25% in principal amount of the
Outstanding Securities of each series affected (with each series voting as a
separate class) shall have made written request to the Trustee to institute
proceedings in respect of such Event of Default in its own name as Trustee
hereunder;

         (c) such Holder or Holders have offered to the Trustee reasonable
indemnity against the costs, expenses and liabilities to be incurred in
compliance with such request;

         (d) the Trustee for 60 days after its receipt of such notice, request
and offer of indemnity has failed to institute any such proceeding; and

         (e) no direction inconsistent with such written request has been given
to the Trustee during such 60-day period by the Holders of a majority in
principal amount of the Outstanding Securities of each series affected (with
each series voting as a separate class);

it being understood and intended that no one or more Holders shall have any
right in any manner whatever by virtue of, or by availing of, any provision of
this Indenture to affect, disturb or prejudice the rights of any other Holders,
or to obtain or to seek to obtain priority or preference over any other Holders
or to enforce any right under this Indenture, except in the manner herein
provided and for the equal and ratable benefit of all the Holders.

SECTION 5.08. UNCONDITIONAL RIGHT OF HOLDERS TO RECEIVE PRINCIPAL AND INTEREST

         Notwithstanding any other provision in this Indenture, the Holder of
any Security shall have the right, which is absolute and unconditional, to
receive payment of the principal of (and premium, if any, on) and (subject to
Section 3.07) interest, if any, on such Security on or after the Stated Maturity
expressed in such Security (or, in the case of redemption, the Redemption Date),
and to institute suit for the enforcement of any such payment, and such rights
shall not be impaired without the consent of such Holder.



                                      -27-
<PAGE>   34

SECTION 5.09. RESTORATION OF RIGHTS AND REMEDIES

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

SECTION 5.10. RIGHTS AND REMEDIES CUMULATIVE

         No right or remedy herein conferred upon or reserved to the Trustee or
to the Holders is intended to be exclusive of any other right or remedy, and
every right and remedy shall, to the extent permitted by law, be cumulative and
in addition to every other right and remedy given hereunder or now or hereafter
existing at law or in equity or otherwise. The assertion or employment of any
right or remedy hereunder, or otherwise, shall not prevent the concurrent
assertion or employment of any other appropriate right or remedy.

SECTION 5.11. DELAY OR OMISSION NOT WAIVER

         No delay or omission of the Trustee or of any Holder of any Security to
exercise any right or remedy accruing upon any Event of Default shall impair any
such right or remedy or constitute a waiver of any such Event of Default or an
acquiescence therein. Every right and remedy given by this Article or by law to
the Trustee or to the Holders may be exercised from time to time, and as often
as may be deemed expedient, by the Trustee or by the Holders, as the case may
be.

SECTION 5.12. CONTROL BY HOLDERS

         The Holders of a majority in principal amount of the outstanding
Securities of each series affected (each series voting as a separate class)
shall have the right to direct the time, method and place of conducting any
proceeding for any remedy available to the Trustee or exercising any trust or
power conferred on the Trustee, with respect to the Securities of such series,
provided that

         (a) such direction shall not be in conflict with any rule of law or
with this Indenture and

         (b) the Trustee may take any other action deemed proper by the Trustee
which is not inconsistent with such direction.



                                      -28-
<PAGE>   35


SECTION 5.13. WAIVER OF PAST DEFAULTS

          The Holders of not less than a majority in principal amount of the
Outstanding Securities of each series (each series voting as a separate class)
may on behalf of the Holders of all the Securities of such series waive any past
default hereunder with respect to such series and its consequences, except a
default

         (a) in the payment of the principal of (and premium, if any, on) or
interest, if any, on any Security or

         (b) in respect of a covenant or provision hereof which under Article
Nine cannot be modified or amended without the consent of the Holder of each
Outstanding Security of such series affected.

         Upon any such waiver, such default shall cease to exist, and any Event
of Default arising therefrom shall be deemed to have been cured, for every
purpose of this Indenture; but no such waiver shall extend to any subsequent or
other default or impair any right consequent thereon.

SECTION 5.14. UNDERTAKING FOR COSTS

         All parties to this Indenture agree, and each Holder of any Security by
his acceptance thereof shall be deemed to have agreed, that any court may in its
discretion require, in any suit for the enforcement of any right or remedy under
this Indenture, or in any suit against the Trustee for any action taken or
omitted by it as Trustee, the filing by any party litigant in such suit of an
undertaking to pay the costs of such suit, and that such court may in its
discretion assess reasonable costs, including reasonable attorneys' fees,
against any party litigant in such suit, having due regard to the merits and
good faith of the claims or defenses made by such party litigant; but the
provisions of this Section 5.14 shall not apply to any suit instituted by the
Trustee, to any suit instituted by any Holder, or group of Holders, holding in
the aggregate more than 10% in principal amount of the Outstanding Securities of
each series affected, or to any suit instituted by any Holder for the
enforcement of the payment of the principal of (or premium, if any, on) or
interest, if any, on any Security of such series on or after the Stated Maturity
expressed in such Security (or, in the case of redemption, on or after the
Redemption Date).

 SECTION 5.15. WAIVER OF STAY OR EXTENSION LAWS

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




                                      -29-
<PAGE>   36

                                     ARTICLE SIX - THE TRUSTEE

SECTION 6.01. CERTAIN DUTIES AND RESPONSIBILITIES

         (a) With respect to the Securities of any series, except during the
continuance of an Event of Default with respect to Securities of such series,

                  (1) the Trustee undertaken to perform such duties and only
such duties as are specifically set forth in this Indenture, and no implied
covenants or obligations shall be read into this Indenture against the Trustee
and

                  (2) in the absence of bad faith on its part, the Trustee may
conclusively rely, as to the truth of the statements and the correctness of the
opinions expressed therein, upon certificates or opinions furnished to the
Trustee and conforming to the requirements of this Indenture; but in the case of
any such certificates or opinions which by any provision hereof are specifically
required to be furnished to the Trustee, the Trustee shall be under a duty to
examine the same to determine whether or not they conform to the requirements of
this Indenture.

         (b) In case an Event of Default with respect to the Securities of any
series has occurred and is continuing, the Trustee shall, with respect to the
Securities of such series, exercise such of the rights and powers vested in it
by this Indenture, and use the same degree of care and skill in their exercise,
as a prudent person would exercise or use under the circumstances in the conduct
of such person's own affairs.

         (c) No provision of this Indenture shall be construed to relieve the
Trustee from liability for its own negligent action, its own negligent failure
to act or its own willful misconduct, except that

                  (1) this paragraph (c) shall not be construed to limit the 
effect of paragraph (a) of this Section 6.01;

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

                  (3) the Trustee shall not be liable with respect to any action
taken or omitted to be taken by it with respect to the Securities of any series
in good faith in accordance with the direction of the Holders of a majority in
principal amount of the outstanding Securities of such series relating to the
time, method and place of conducting any proceeding for any remedy available to
the Trustee, or exercising any trust or power conferred upon the Trustee, under
this Indenture.

No provision of this Indenture shall require the Trustee to expend or risk its
own funds or otherwise incur any financial liability in the performance of any
of its duties hereunder, or in the 



                                      -30-
<PAGE>   37

exercise of any of its rights or powers, if it shall have reasonable grounds for
believing that repayment of such funds or adequate indemnity against such risk
or liability is not reasonably assured to it.

SECTION 6.02. NOTICE OF DEFAULTS

         Within 90 days after the occurrence of any default hereunder with
respect to the Securities of any series, the Trustee shall transmit by mail to
all Holders of such series entitled to receive reports pursuant to Section
7.04(c), notice of such default hereunder known to the Trustee, unless such
default shall have been cured or waived; provided, however, that, except in the
case of a default in the payment of the principal of (and premium, if any) or
interest, if any, on any Security of such series, the Trustee shall be protected
in withholding such notice if and so long as the Board of Directors, the
executive committee or a trust committee of directors or Responsible Officers of
the Trustee in good faith determine that the withholding of such notice is in
the interest of the Holders; and provided, further, that in the case of any
default of the character specified in section 5.01(4) with respect to Securities
of such series, no such notice to Holders shall be given until at least 30 days
after the occurrence thereof. For the purpose of this Section 6.02, the term
"default" means any event which is, or after notice or lapse of time or both
would become, an Event of Default with respect to Securities of such series.

SECTION 6.03. CERTAIN RIGHTS OF TRUSTEE

         Except as otherwise provided in section 6.01:

         (a) the Trustee may rely and shall be protected in acting or refraining
from acting upon any resolution, certificate, statement, instrument, opinion,
report, notice, request, direction, consent, order, bond, debenture, note or
other paper or document believed by it to be genuine and to have been signed or
presented by the proper party or parties;

         (b) any request or direction of the Company mentioned herein shall be
sufficiently evidenced by a Company Request or Company Order and any resolution
of the Board of Directors may be sufficiently evidenced by a Board Resolution;

         (c) whenever in the administration of this Indenture the Trustee shall
deem it desirable that a matter be proved or established prior to taking,
suffering or omitting any action hereunder, the Trustee (unless other evidence
be herein specifically prescribed) may, in the absence of bad faith on its part,
rely upon an officers' Certificate;

         (d) the Trustee may consult with counsel and the written advice of such
counsel or any opinion of Counsel shall be full and complete authorization and
protection in respect of any action taken, suffered or omitted by it hereunder
in good faith and in reliance thereon;

         (e) the Trustee shall be under no obligation to exercise any of the
rights or powers vested in it by this Indenture at the request or direction of
any of the Holders pursuant to this Indenture, unless such Holders shall have
offered to the Trustee reasonable security or indemnity 



                                      -31-
<PAGE>   38

against the costs, expenses and liabilities which might be incurred by it in
compliance with such request or direction;

         (f) the Trustee shall not be bound to make any investigation into the
facts or matters stated in any resolution, certificate, statement, instrument,
opinion, report, notice, request, direction, consent, order, bond, debenture,
note or other paper or document, but the Trustee, in its discretion, may make
such further inquiry or investigation into such facts or matters as it may see
fit, and, if the Trustee shall determine to make such further inquiry or
investigation, it shall be entitled to examine the books, records and promises
of the Company, personally or by agent or attorney; and

         (g) the Trustee may execute any of the trusts or powers hereunder or
perform any duties hereunder either directly or by or through agents or
attorneys and the Trustee shall not be responsible for any misconduct or
negligence on the part of any agent or attorney appointed with due care by it
hereunder.

SECTION 6.04. NOT RESPONSIBLE FOR RECITALS OR ISSUANCE OF SECURITIES

         The recitals contained herein and in the Securities, except the
Trustee's certificates of authentication, shall be taken as the statements of
the Company, and the Trustee assumes no responsibility for their correctness.
The Trustee makes no representations as to the validity or sufficiency of this
Indenture or of the Securities. The Trustee shall not be accountable for the use
or application by the Company of Securities or the proceeds thereof.

SECTION 6.05. MAY HOLD SECURITIES

         The Trustee, any Paying Agent, any Securities Registrar or any other
agent of the Company, in its individual or any other capacity, may become the
owner or pledgee of Securities and, subject to Sections 6.08 and 6.13, may
otherwise deal with the Company with the same rights it would have if it were
not the Trustee, Paying Agent, Securities Registrar or such other agent.

SECTION 6.06. MONEY HELD IN TRUST

         Money held by the Trustee in trust hereunder need not be segregated
from other funds except to the extent required by law. The Trustee shall be
under no liability for interest on any money received by it hereunder except as
otherwise agreed with the Company.

SECTION 6.07. COMPENSATION AND REIMBURSEMENT

         The Company agrees

         (a) to pay to the Trustee from time to time reasonable compensation for
all services rendered by it hereunder (which compensation shall not be limited
by any provision of law in regard to the compensation of a trustee of an express
trust);



                                      -32-
<PAGE>   39

         (b) except as otherwise expressly provided herein, to reimburse the
Trustee upon its request for all reasonable expenses, disbursements and advances
incurred or made by the Trustee in accordance with any provision of this
Indenture (including the reasonable compensation and the expenses and
disbursements of its agents and counsel) except any such expense, disbursement
or advance as may be attributable to its negligence or bad faith; and

         (c) to indemnify the Trustee for, and to hold it harmless against, any
loss, liability or expense incurred without negligence or bad faith on its part,
arising out of or in connection with the acceptance or administration of this
trust, including the costs and expenses of defending itself against any claim or
liability in connection with the exercise or performance of any of its powers or
duties hereunder.

          As security for the performance of the obligations of the Company
under this Section 6.07, the Trustee shall have a lien prior to the Securities
upon all property and funds held or collected by the Trustee as such, except
funds held in trust for the payment of principal of or interest, if any, on the
Securities.

SECTION 6.08. DISQUALIFICATION; CONFLICTING INTERESTS

          If the Trustee has or shall acquire any conflicting interest within
the meaning of the Trust Indenture Act with respect to the Securities of any
series, it shall either eliminate such conflicting interest or resign with
respect to the Securities of such series, to the extent and in the manner
provided by, and subject to the provisions of, the Trust Indenture Act and this
Indenture.

          The following Indentures between the Company and the Trustee shall be
excluded from the application of Section 310(b)(1) of the Trust Indenture Act:
Indentures dated as of October 1, 1988; May 1, 1987 and August 1, 1987.

SECTION 6.09. CORPORATE TRUSTEE REQUIRED; ELIGIBILITY

          There shall at all times be a Trustee hereunder with respect to each
series of Securities which shall be a Person eligible under the Trust Indenture
Act, having a combined capital and surplus of at least $50,000,000 and subject
to supervision or examination by Federal or State authority. If such corporation
publishes reports of condition at least annually, pursuant to law or to the
requirements of said supervising or examining authority, then for the purposes
of this Section 6.09, the combined capital and surplus of such corporation shall
be deemed to be its combined capital and surplus as set forth in its most recent
report of condition so published. No obligor of the Securities or Person
directly or indirectly controlling, controlled by or under common control with
such obligor shall serve as Trustee upon such Securities. If at any time the
Trustee shall cease to be eligible in accordance with the provisions of this
Section 6.09, it shall resign immediately in the manner and with the effect
hereinafter specified in this Article Six.





                                      -33-
<PAGE>   40

SECTION 6.10. RESIGNATION AND REMOVAL; APPOINTMENT OF SUCCESSOR

          (a) No resignation or removal of the Trustee and no appointment of a
successor Trustee pursuant to this Article Six shall become effective until the
acceptance of appointment by the successor Trustee under Section 6.11.

          (b) The Trustee may resign at any time with respect to the Securities
of one or more series by giving written notice thereof to the Company. If an
instrument of acceptance by a successor Trustee shall not have been delivered to
the Trustee within 30 days after the giving of such notice of resignation, the
resigning Trustee may petition any court of competent jurisdiction for the
appointment of a successor Trustee.

          (c) The Trustee may be removed at any time with respect to the
Securities of any series by Act of the Holders of a majority in principal amount
of the Outstanding Securities of such series, delivered to the Trustee and to
the Company.

          (d) If at any time with respect to any series of Securities:

                   (1) the Trustee shall fail to comply with Section 6.08 after
written request therefor by the Company or by any Holder who has been a bona
fide Holder of a Security of such series for at least six months, or

                   (2) the Trustee shall cease to be eligible under Section 6.09
and shall fail to resign after written request therefor by the Company or by
any such Holder, or

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

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

         (e) If the Trustee shall resign, be removed or become incapable of
acting, or if a vacancy shall occur in the office of Trustee for any cause with
respect to the Securities of one or more series, the Company, by a Board
Resolution, shall promptly appoint a successor Trustee or Trustees with respect
to the Securities of that or those series (it being understood that any such
successor Trustee may be appointed with respect to the Securities of one or more
or all of such series and that at any time there shall be only one Trustee with
respect to the Securities of any particular series). If, within one year after
such resignation, removal or incapability, or the occurrence of such vacancy, a
successor Trustee with respect to the Securities of any series shall be
appointed by Act of the Holders of a majority in principal amount of the
Outstanding 



                                      -34-
<PAGE>   41

Securities of such series delivered to the Company and the retiring Trustee, the
successor Trustee so appointed shall, forthwith upon its acceptance of such
appointment in accordance with Section 6.11, become the successor Trustee with
respect to the securities of such series and to that extent supersede the
successor Trustee appointed by the Company. If no successor Trustee shall have
been so appointed by the Company or the Holders and accepted appointment in the
manner hereinafter provided, any Holder who has been a bona fide Holder of a
Security for at least six months may, on behalf of himself and all others
similarly situated, petition any court of competent jurisdiction for the
appointment of a successor Trustee.

          (f) The Company shall give notice of each resignation and each removal
of the Trustee and each appointment of a successor Trustee by mailing written
notice of such event by first-class mail, postage prepaid, to the Holders of the
Securities of one or more or all series, as the case may be, to which the
resignation, removal or appointment relates, as their names and addresses appear
in the Securities Register. Each notice shall include the name of the successor
Trustee and the address of its Corporate Trust Office.

SECTION 6.11. ACCEPTANCE OF APPOINTMENT BY SUCCESSOR

          (a) In case of the appointment hereunder of a successor Trustee with
respect to all Securities, every such successor Trustee so appointed shall
execute, acknowledge and deliver to the Company and to the retiring Trustee an
instrument accepting such appointment, and thereupon the resignation or removal
of the retiring Trustee shall become effective and such successor Trustee,
without any further act, deed or conveyance, shall become vested with all the
rights, powers, trusts and duties of the retiring Trustee; but, on request of
the Company or the successor Trustee, such retiring Trustee shall, upon payment
of its charges, execute and deliver an instrument transferring to such successor
Trustee all the rights, powers and trusts of the retiring Trustee and shall duly
assign, transfer and deliver to such successor Trustee all property and money
held by such retiring Trustee hereunder, subject, nevertheless to its lien, if
any, provided for in Section 6.07.

          (b) In case of the appointment hereunder of a successor Trustee with
respect to the Securities of one or more (but not all) series, the Company, the
retiring Trustee and each successor Trustee with respect to the Securities of
one or more series shall execute and deliver an indenture supplemental hereto
wherein each successor Trustee shall accept such appointment and which (i) shall
contain such provisions as shall be necessary or desirable to transfer and
confirm to, and to vest in, each successor Trustee all the rights, powers,
trusts and duties of the retiring Trustee with respect to the Securities of that
or those series to which the appointment of such successor Trustee relates, (ii)
if the retiring Trustee is not retiring with respect to all Securities, shall
contain such provisions as shall be deemed necessary or desirable to confirm
that all the rights, powers, trusts and duties of the retiring Trustee with
respect to the Securities of that or those series as to which the retiring
Trustee is not retiring shall continue to be vested in the retiring Trustee, and
(iii) shall add to or change any of the provisions of this Indenture as shall be
necessary to provide for or facilitate the administration of the trusts
hereunder by more than one Trustee, it being understood that nothing herein or
in such supplemental indenture shall constitute such Trustees co-trustees of the
same trust and that each such Trustee shall be trustee 



                                      -35-
<PAGE>   42

of a trust or trusts hereunder separate and apart from any trust or trusts
hereunder administered by any other such Trustee; and, upon the execution and
delivery of such supplemental indenture, the resignation or removal of the
retiring Trustee shall become effective to the extent provided therein and each
such successor Trustee, without any further act, deed or conveyance, shall
become vested with all the rights, powers, trusts and duties of the retiring
Trustee with respect to the Securities of that or those series to which the
appointment of such successor Trustee relates; but, on request of the Company or
any successor Trustee, such retiring Trustee shall duly assign, transfer and
deliver to such successor Trustee all property and money held by such retiring
Trustee hereunder with respect to the Securities of that or those series to
which the appointment of such successor Trustee relates.

         (c) Upon request of any such successor Trustee, the Company shall
execute any and all instruments for more fully and certainly vesting in and
confirming to such successor Trustee all such rights, powers and trusts referred
to in paragraph (a) or (b) of this Section 6.11, as the case may be.

         (d) No successor Trustee shall accept its appointment unless at the
time of such acceptance such successor Trustee shall be qualified and eligible
under this Article Six.

SECTION 6.12. MERGER, CONVERSION, CONSOLIDATION OR SUCCESSION TO BUSINESS

         Any corporation into which the Trustee may be merged or converted or
with which it may be consolidated, or any corporation resulting from any merger,
conversion or consolidation to which the Trustee shall be a party, or any
corporation succeeding to all or substantially all the corporate trust business
of the Trustee, shall be the successor of the Trustee hereunder, provided such
corporation shall be otherwise qualified and eligible under this Article Six,
without the execution or filing of any paper or any further act on the part of
any of the parties hereto. In case any Securities shall have been authenticated,
but not delivered, by the Trustee then in office, any successor by merger,
conversion or consolidation to such authenticating Trustee may adopt such
authentication and deliver the Securities so authenticated with the same effect
as if such successor Trustee had itself authenticated such Securities.

SECTION 6.13. PREFERENTIAL COLLECTION OF CLAIMS AGAINST COMPANY

         If and when the Trustee shall become a creditor of the Company (or any
other obligor of the Securities), the Trustee shall be subject to the terms of
the Trust Indenture Act regarding collection of claims against the Company (or
such obligor).


           ARTICLE SEVEN - HOLDERS' LISTS AND REPORTS BY TRUSTEE AND
                                    COMPANY

SECTION 7.01. COMPANY TO FURNISH TRUSTEE NAMES AND ADDRESSES OF HOLDERS

         The Company will furnish or cause to be furnished to the Trustee:



                                      -36-
<PAGE>   43

         (a) semiannually, not more than 15 days after each Record Date, a list,
in such form as the Trustee may reasonably require, of the names and addresses
of the Holders as of such Record Date and

         (b) at such other times as the Trustee may request in writing, within
30 days after the receipt by the Company of any such request, a list of similar
form and content as of a date not more than 15 days prior to the time such list
is furnished;

excluding from any such list names and addresses received by the Trustee in its
capacity as Securities Registrar.

SECTION 7.02. PRESERVATION OF INFORMATION; COMMUNICATIONS TO HOLDERS

         (a) The Trustee shall preserve, in as current a form as is reasonably
practicable, (i) the names and addresses of Holders contained in the most recent
list furnished to the Trustee as provided in Section 7.01 and (ii) the names and
addresses of Holders received by the Trustee in its capacity as Securities
Registrar. The Trustee may destroy any list furnished to it as provided in
Section 7.01 upon receipt of a new list so furnished.

         (b) Holders may communicate as provided in Section 312(b) of the Trust
Indenture Act with other Holders with respect to their rights under this
Indenture or under the Securities.

         (c) Every Holder of Securities, by receiving and holding the same,
agrees with the Company and the Trustee that neither the Company nor the Trustee
nor any agent of either of them shall be held accountable by reason of the
disclosure of any such information as to the names and addresses of the Holders
in accordance with paragraph (b) of this Section 7.02, regardless of the source
from which such information was derived, and that the Trustee shall not be held
accountable by reason of mailing any material pursuant to a request made under
paragraph (b) of this Section 7.02.

SECTION 7.03. REPORTS BY TRUSTEE

         (a) Within 60 days after June 15 of each year commencing with June 15,
1992, the Trustee shall transmit to Holders such reports concerning the Trustee
and its actions under this Indenture as may be required under the Trust
Indenture Act at the time and in the manner provided therein.

         (b) A copy of each such report shall, at the time of transmission to
Holders, be filed by the Trustee with each stock exchange upon which the
Securities are listed, with the Commission and with the Company. The Company
will notify the Trustee when the Securities are listed on any stock exchange.



                                      -37-
<PAGE>   44

SECTION 7.04. REPORTS BY COMPANY

         (a) The Company shall file with the Trustee, within 15 days after the
Company is required to file the same with the Commission, copies of the annual
reports and of the information, documents and other reports (or copies of such
portions of any of the foregoing as the Commission may from time to time by
rules and regulations prescribe) which the Company in required to file with the
Commission pursuant to Section 13 or Section 15(d) of the Securities Exchange
Act of 1934, as amended; or, if the Company is not required to file information,
documents or reports pursuant to either of such Sections, then to file with the
Trustee and the Commission, in accordance with rules and regulations prescribed
by the Commission, such of the supplementary and periodic information, documents
and reports which may be required pursuant to Section 13 of the Securities
Exchange Act of 1934, as amended, in respect of a security listed and registered
on a national securities exchange as may be prescribed in such rules and
regulations.

         (b) The Company shall file with the Trustee and the Commission, in
accordance with the rules and regulations prescribed by the Commission, such
additional information, documents, and reports with respect to compliance by the
Company with the conditions and covenants provided for in this Indenture as may
be required by such rules and regulations.

         (c) The Company shall transmit to the Holders within 30 days after the
filing thereof with the Trustee, by first-class mail, such summaries of any
information, documents and reports required to be filed by the Company pursuant
to paragraphs (a) and (b) of this Section 7.04 as may be required by rules and
regulations prescribed by the Commission.

         (d) The Company shall furnish to the Trustee, within 120 days after the
end of each fiscal year, a brief certificate from the principal executive
officer, principal financial officer or principal accounting officer as to his
or her knowledge of the Company's compliance with all conditions and covenants
under this Indenture. For purposes of this paragraph (d), such compliance shall
be determined without regard to any period of grace or requirement of notice
provided under this Indenture.


         ARTICLE EIGHT - CONSOLIDATION, MERGER, CONVEYANCE, TRANSFER OR
                                      LEASE

SECTION 8.01. COMPANY MAY CONSOLIDATE, ETC., ONLY ON CERTAIN TERMS

         The Company shall not consolidate with or merge into any other
corporation or convey, transfer or lease its properties and assets substantially
as an entirety to any Person, unless:

          (1) in case the Company shall consolidate with or merge into another
corporation or convey, transfer or lease its properties and assets substantially
as an entirety to any Person, the corporation formed by such consolidation or
into which the Company is merged or the Person which acquires by conveyance or
transfer, or which leases, the properties and assets of the 



                                      -38-
<PAGE>   45

Company substantially as an entirety shall be a corporation organized and
existing under the laws of the United States of America, any state thereof or
the District of Columbia and shall expressly assume, by an indenture
supplemental hereto, executed and delivered to the Trustee, in form satisfactory
to the Trustee, the due and punctual payment of the principal of and interest,
if any, on all the Securities and the performance of every covenant of this
Indenture on the part of the Company to be performed or observed;

          (2) immediately after giving effect to such transaction, no Event of
Default, and no event which, after notice or lapse of time or both, would become
an Event of Default, shall have occurred and be continuing; and

          (3) the Company has delivered to the Trustee an officers' Certificate
and an Opinion of Counsel, each stating that such consolidation, merger,
conveyance, transfer or lease and, if a supplemental indenture is required in
connection with such transaction, such supplemental indenture comply with this
Article Eight and that all conditions precedent herein provided for relating to
such transaction have been complied with.

SECTION 8.02. SUCCESSOR CORPORATION SUBSTITUTED

         Upon any consolidation or merger by the Company with or into any other
corporation or any conveyance, transfer or lease of the properties and assets of
the Company substantially as an entirety to any Person in accordance with
Section 8.01, the successor corporation formed by such consolidation or into
which the Company in merged or to which such conveyance, transfer or lease is
made shall succeed to, and be substituted for, and may exercise every right and
power of, the Company under this Indenture with the same effect as if such
successor corporation had been named as the Company herein, and thereafter,
except in the case of a lease to another Person, the predecessor corporation
shall be relieved of all obligations and covenants under this Indenture and the
Securities.


                     ARTICLE NINE - SUPPLEMENTAL INDENTURES

SECTION 9.01. SUPPLEMENTAL INDENTURES WITHOUT CONSENT OF HOLDERS

         Without the consent of any Holders, the Company, when authorized by a
Board Resolution, and the Trustee, at any time and from time to time, may enter
into one or more indentures supplemental hereto, in form satisfactory to the
Trustee, for any of the following purposes:

          (1) to evidence the succession of another corporation to the Company
and the assumption by any such successor of the covenants of the Company herein
and in the Securities; or

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




                                      -39-
<PAGE>   46
          (3) to secure the Securities; or

          (4) to cure any ambiguity, to correct or supplement any provision
herein which may be inconsistent with any other provision herein, or to make any
other provisions with respect to matters or questions arising under this
Indenture, provided such action shall not adversely affect the interests of the
Holders in any material respect; or

          (5) to evidence and provide for the acceptance of appointment
hereunder by a successor trustee with respect to the Securities of one or more
series and to add to or change any of the provisions of this Indenture as shall
be necessary to provide for or facilitate the administration of the trusts
hereunder by more than one trustee, pursuant to the requirements of Section
6.11.

SECTION 9.02. SUPPLEMENTAL INDENTURES WITH CONSENT OF HOLDERS

         With the consent of the Holders of not less than a majority in
principal amount of the Securities at the time outstanding of all series
affected by such supplemental indenture (each such series voting as a separate
class), by Act of said Holders delivered to the Company and the Trustee, the
Company, when authorized by a Board Resolution, and the Trustee may enter into
an indenture or indentures supplemental hereto for the purpose of adding any
provisions to or changing in any manner or eliminating any of the provisions of
this Indenture or of modifying in any manner the rights of the Holders of
Securities of such series under this Indenture; provided, however, that no such
supplemental indenture shall, without the consent of the Holder of each
Outstanding Security affected thereby,

         (1) change the Stated Maturity of the principal of (or premium, if any,
on), or any installment of principal of or interest, if any, on, any Security,
or reduce the principal amount thereof or the interest thereon, or change the
place of payment where, or the coin or currency in which, any Security or the
interest thereon is payable, or impair the right to institute suit for the
enforcement of any such payment on or after the Stated Maturity thereof, or

         (2) reduce the percentage in principal amount of the Outstanding
Securities, the consent of whose Holders is required for any such supplemental
indenture, or the consent of whose Holders is required for any waiver (of
compliance with certain provisions of this Indenture or certain defaults
hereunder and their consequences) provided for in this Indenture, or

         (3) modify any of the provisions of this Section 9.02, Section 5.13 or
Section 10.05, except to increase any such percentage or to provide that certain
other provisions of this Indenture cannot be modified or waived without the
consent of the Holder of each Outstanding Security affected thereby.

         A supplemental indenture that changes or eliminates any covenant or
other provision of this Indenture which has expressly been included solely for
the benefit of one or more particular series of Securities, or that modifies the
rights of the Holders of Securities of such series with 


                                      -40-
<PAGE>   47

respect to such covenant or other provision, shall be deemed not to affect the
rights under this Indenture of the Holders of Securities of any other series.

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

SECTION 9.03. EXECUTION OF SUPPLEMENTAL INDENTURES

         In executing, or accepting the additional trusts created by, any
supplemental indenture permitted by this Article Nine or the modifications
thereby of the trusts created by this Indenture, the Trustee shall be entitled
to receive, and shall be fully protected in relying upon, an opinion of Counsel
stating that the execution of such supplemental indenture is authorized or
permitted by this Indenture. The Trustee may, but shall not be obligated to,
enter into any such supplemental indenture which affects the Trustee's own
rights, duties or immunities under this Indenture or otherwise.

SECTION 9.04. EFFECT OF SUPPLEMENTAL INDENTURES

         Upon the execution of any supplemental indenture under this Article
Nine, this Indenture shall be modified in accordance therewith, and such
supplemental indenture shall form a part of this Indenture for all purposes; and
every Holder of Securities theretofore or thereafter authenticated and delivered
hereunder shall be bound thereby.

SECTION 9.05. CONFORMITY WITH TRUST INDENTURE ACT

         Every supplemental indenture executed pursuant to this Article Nine
shall conform to the requirements of the Trust Indenture Act as then in effect.

SECTION 9.06. REFERENCE IN SECURITIES TO SUPPLEMENTAL INDENTURES

         Securities authenticated and delivered after the execution of any
supplemental indenture pursuant to this Article Nine may, and shall, if required
by the Trustee, bear a notation in form approved by the Trustee as to any matter
provided for in such supplemental indenture. If the Company shall so determine,
new Securities so modified as to conform, in the opinion of the Trustee and the
Board of Directors, to any such supplemental indenture may be prepared and
executed by the Company and authenticated and delivered by the Trustee in
exchange for Outstanding Securities.




                                      -41-
<PAGE>   48




                             ARTICLE TEN - COVENANTS

SECTION 10.01. PAYMENT OF PRINCIPAL AND INTEREST

         For the benefit of each series of Securities, the Company will duly and
punctually pay the principal of (and premium, if any) and interest, if any, on
the Securities of that series in accordance with the terms of such Securities
and this Indenture.

SECTION 10.02. MAINTENANCE OF OFFICE OR AGENCY

         The Company will maintain in the Borough of Manhattan, The City of New
York, an office or agency where Securities may be presented or surrendered for
payment, where Securities may be surrendered for registration of transfer or
exchange and where notices and demands to or upon the Company in respect of the
Securities and this Indenture may be served. The Company will give prompt
written notice to the Trustee of the location, and any change in the location,
of such office or agency. If at any time the Company shall fail to maintain Any
such required office or agency or shall fail to furnish the Trustee with the
address thereof, such presentations, surrenders, notices and demands may be made
or served at the Corporate Trust Office of the Trustee, and the Company hereby
appoints the Trustee as its agent to receive all such presentations, surrenders,
notices and demands.

          The Company may also from time to time designate one or more other
offices or agencies (in or outside The City of New York) where the Securities
may be presented or surrendered for any or all such purposes and may from time
to time rescind such designations; provided, however, that no such designation
or rescission shall in any manner relieve the Company of its obligation to
maintain an office or agency in the Borough of Manhattan, The City of New York,
for such purposes. The Company will give prompt written notice to the Trustee of
any such designation or rescission and of any change in the location of any such
other office or agency.

SECTION 10.03. MONEY FOR SECURITY PAYMENTS TO BE HOLD IN TRUST

          If the Company shall at any time act as its own Paying Agent with
respect to any series of Securities, it will, on or before each due date of the
principal of (or premium, if any) or interest, if any, on any of the Securities
of that series, segregate and hold in trust for the benefit of the Persons
entitled thereto a sum sufficient to pay the principal (or premium, if any) or
interest, if any, so becoming due until such sums shall be paid to such Persons
or otherwise disposed of as herein provided and will promptly notify the Trustee
of its action or failure so to act.

          Whenever the Company shall have one or more Paying Agents, it will, on
each due date of the principal of (or premium, if any) or interest, if any, on
any Securities, deposit with a Paying Agent a sum sufficient to pay the
principal or interest so becoming due, such sum to be held in trust for the
benefit of the Persons entitled to such principal or interest, and (unless such
Paying Agent is the Trustee) the Company will promptly notify the Trustee of its
action or failure so to act.



                                      -42-
<PAGE>   49

         The Company will cause each Paying Agent other than the Trustee to
execute and deliver to the Trustee an instrument in which such Paying Agent
shall agree with the Trustee, subject to the provisions of this Section 10.3,
that such Paying Agent will:

         (a) hold all sums held by it for the payment of the principal of (or
premium, if any) or interest, if any, on Securities in trust for the benefit of
the Persons entitled thereto until such sums shall be paid to such Persons or
otherwise disposed of as herein provided;

         (b) give the Trustee notice of any default by the Company (or any other
obligor upon the Securities of that series) in the making of any payment of
principal of (or premium, if any, on) or interest, if any, on the Securities of
that series when the same shall be due and payable; and

         (c) at any time during the continuance of any such default, upon the
written request of the Trustee, forthwith pay to the Trustee all sums so held in
trust by such Paying Agent.

SECTION 10.04.   LIMITATION ON LIENS AND SALE-LEASEBACKS

         (a) The Company will not, nor will it permit any Subsidiary to, create,
assume, incur or suffer to exist any Mortgage upon any Principal Property,
whether owned or leased on the date of this Indenture or hereafter acquired, to
secure any Debt of the Company or any other Person (other than the Securities),
without in any such case making effective provision whereby all of the
Securities Outstanding shall be directly secured equally and ratably with such
Debt, excluding, however, the following:

                  (i) any Mortgage upon property owned or leased by any
corporation existing at the time such corporation becomes a Subsidiary;

                  (ii) any Mortgage upon property existing at the time of
acquisition thereof;

                  (iii) any Mortgage to secure the payment of all or any part of
the purchase price of property or to secure any Debt incurred prior to, at the
time of or within 180 days after the acquisition of such property for the
purpose of financing all or any part of the purchase price thereof;

                  (iv) any Mortgage upon property to secure all or any part of
the cost of construction, alteration, repair or improvement of all or any part
of such property, or Debt incurred prior to, at the time of or within 180 days
after the completion of such construction, alteration, repair or improvement or
commencement of full operations on such property for the purpose of financing
all or any part of such cost;

                  (v) any Mortgage securing Debt of a Subsidiary owing to the
Company or to another Subsidiary;




                                      -43-
<PAGE>   50

                  (vi) any Mortgage existing at the date of this Indenture; and

                  (vii) any extension, renewal or replacement (or successive
extensions, renewals or replacements) in whole or in part of any Mortgage
referred to in the foregoing clauses (i) to (vi), inclusive; provided, however,
that the principal amount of Debt secured thereby shall not exceed the principal
amount of Debt so secured at the time of such extension, renewal or replacement;
and provided, further, that such Mortgage shall be limited to all or such part
of the property which was subject to the Mortgage so extended, renewed or
replaced (plus improvements on such property).

         Notwithstanding the foregoing provisions of this paragraph (a), the
Company may, and may permit any Subsidiary to, create, assume, incur or suffer
to exist any Mortgage upon any Principal Property which is not excepted by
clauses (i) through (vii) above without equally and ratably securing the
Securities, provided that the aggregate amount of all Debt then outstanding
secured by such Mortgage and all similar Mortgages, together with all net sale
proceeds from Sale-Leaseback Transactions (as defined in paragraph (b) of this
Section 10.4) which are not permitted pursuant to clauses (i) and (ii) of
paragraph (b) of this Section 10.4, does not exceed 10% of the total
consolidated stockholders' equity of the Company as shown on the audited
consolidated balance sheet contained or incorporated by reference in the
Company's latest Annual Report on Form 10-K. For the purpose of this paragraph
(a), no Mortgage to secure any Debt will be deemed to be created by any Mortgage
in favor of the United States of America or any state thereof, or any other
country, or any political subdivision of any of the foregoing, to secure
partial, progress, advance or other payments pursuant to the provisions of any
contract or statute, or any Mortgage securing industrial development, pollution
control or similar revenue bonds.

         (b) The Company will not, nor will it permit any Subsidiary to, sell or
transfer any Principal Property with the Company or any Subsidiary taking back a
lease of such Principal Property (a "Sale-Leaseback Transaction"), unless (i)
such Sale-Leaseback Transaction occurs within 180 days from the date of
acquisition of such Principal Property or the date of the completion of
construction or commencement of full operations on such Principal Property,
whichever is later, or (ii) the Company, within 120 days after such
Sale-Leaseback Transaction, applies or causes to be applied to the retirement of
Funded Debt of the Company or any Subsidiary (other than Funded Debt of the
Company which by its terms or the terms of the instrument pursuant to which it
was issued is subordinate in right of payment to the Securities) an amount not
less than the net proceeds of the sale of such Principal Property.

         Notwithstanding the foregoing provisions of this paragraph (b), the
Company may, and may permit any Subsidiary to, effect any Sale-Leaseback
Transaction involving any Principal Property, provided that the net sale
proceeds from such Sale-Leaseback Transaction, together with all Debt secured by
Mortgages not specifically excluded pursuant to clauses (i) through (vii) of
paragraph (a) of this Section 10.4 from the operation of such paragraph (a),
does not exceed 10% of the total consolidated stockholders' equity of the
Company as shown on the audited consolidated balance sheet contained or
incorporated by reference in the Company's latest Annual Report on Form 10-K.
The provisions of this paragraph (b) shall also not prevent any 



                                      -44-
<PAGE>   51

Sale-Leaseback Transaction involving a lease for a period, including renewals,
of not more than 36 months.

SECTION 10.05. DIVIDENDS ON AND ACQUISITIONS OF STOCK

         As long as more than 50% of the Company's Common Stock is owned by
Burlington Resources Inc. ("BR"), the company will not declare or pay any
dividend or make any distribution upon any of its stock (other than in Common
Stock of the Company), or make, cause or permit any of its Subsidiaries to make
any payment (other than in Common Stock of the Company) for the purchase,
redemption or retirement of any shares of Common Stock of the Company, unless
immediately after such payment or distribution the aggregate amount of all such
payments and distributions made subsequent to December 31, 1991 shall not have
exceeded the total of (i) the consolidated net income of the Company and its
Subsidiaries arising subsequent to December 31, 1991, (ii) any contribution to
the capital of the Company, and any consideration which shall have been received
by the Company after December 31, 1991, with respect to the issue or sale of any
of its Common Stock in excess of amounts expended after such date for the
purchase, redemption or other acquisition of any shares of such Common Stock,
(iii) the aggregate principal amount of any indebtedness and the aggregate
involuntary liquidation preference (other than accrued and unpaid dividends) of
any shares of any class of stock ranking senior to the Common Stock in respect
of dividends or assets of the Company or a Subsidiary which after such date
shall have been converted into Common Stock of the Company, and (iv) $50
million; provided, however, that the provisions of this Section 10.05 shall not
prevent or restrict (A) the dividend to BR of the balance owed by BR to the
Company under an intercorporate cash management arrangement, and such dividend
shall not be included in any computation made under this Section 10.05; (B) any
payment of any dividend on any shares of stock of the Company ranking senior to
the Common Stock in respect of dividends or assets (other than shares of such
senior stock issued in exchange for Common Stock of the Company), but the
amounts of any such payments shall be included in the calculations contemplated
by the foregoing provisions of this Section 10.05; (C) the redemption,
acquisition or retirement of any shares of Common Stock of the Company in
exchange for, or out of the proceeds of the concurrent sale of, other shares of
its Common Stock, and neither any such redemption, acquisition or retirement nor
the proceeds of any such sale (to the extent used for such purposes) shall be
included in any computation made under this Section 10.05; (D) the purchase of
any shares of Common Stock of the Company with moneys accumulated for such
purpose pursuant to or in connection with any retirement, bonus, profit sharing,
thrift, savings, stock option or compensation plan for officers or employees of
the Company or any Subsidiary, and no payment made for any such purchase (or
funds received by the Company with respect to any such shares) shall be included
in any computation made under this Section 10.05; or (E) the conversion of
shares of any class of stock of the Company into shares of any other class of
stock of the Company, and no such conversion shall be included in any
computation made under this Section 10.05 otherwise than in accordance with
clause (iii) above.

         For the purpose of this Section 10.05, in determining at any time the
amount of consolidated net income arising subsequent to December 31, 1991,
adjustments, if any, required to eliminate the effect of charges or credits to
income or to retained earnings which result in a 



                                      -45-
<PAGE>   52

reduction or addition to consolidated net income or retained earnings arising
subsequent to December 31, 1991 shall be made for the following:

               (A) charges for the write-down or write-off or amortization of
the excess of the cost to the Company or a Subsidiary of properties acquired
as entireties or otherwise over the original cost of such properties when
first devoted to public use, which may be required by any rule, regulation or
order of any public body or authority exercising regulatory authority over the
accounts of the Company or such Subsidiary; and

                (B) charges or credits applicable to a period or periods prior
to January 1, 1992, regardless of when recorded.

         For the purposes of this Section 10.05, in determining at any time the
amount of any distribution upon, or consideration applied to the purchase,
redemption or other acquisition of, shares of stock of the company in any case
in which such distribution or consideration is, in whole or in part, in the form
of property of any nature owned by the Company or a Subsidiary, the amount of
such distribution or consideration represented by such property shall be taken
as the net amount (after deducting any applicable reserves) at which such
property is carried on the books of the Company or such Subsidiary, as the case
may be, at the date of such distribution, purchase, redemption or other
acquisition.

SECTION 10.06. WAIVER OF CERTAIN COVENANTS

         The Company may omit in any particular instance to comply with any
covenant or condition set forth in Section 10.04 or 10.05 if, before or after
the time for such compliance, the Holders of at least a majority in principal
amount of the Outstanding Securities of each series shall, by notice to the
Trustee, either waive such compliance in such instance or generally waive
compliance with such covenant or condition, but no such waiver shall extend to
or affect such covenant or condition except to the extent so expressly waived,
and, until such waiver shall become effective, the obligations of the Company
and the duties of the Trustee in respect of any such covenant or condition shall
remain in full force and effect.


                    ARTICLE ELEVEN - REDEMPTION OF SECURITIES

SECTION 11.01. APPLICABILITY OF ARTICLE

         Securities of any series which are redeemable before their Stated
Maturity shall be redeemable in accordance with their terms and (except as
otherwise specified, as contemplated by Section 3.01 for Securities of any
series) in accordance with this Article Eleven; Provided, however, that if any
provision of any such Security shall conflict with any provision of this Article
Eleven, the provision of such Security shall govern. Except as otherwise set
forth in any Security, each Security shall be subject to partial redemption only
in the amount of $1,000 or integral multiples thereof.



                                      -46-
<PAGE>   53

SECTION 11.02. ELECTION TO REDEEM; NOTICE TO TRUSTEE

         The right of the Company to elect to redeem any Securities of any
series shall be set forth in the terms of such Securities of such series
established in accordance with Section 3.01. In case of any redemption at the
election of the Company of less than all the Securities of any series, the
Company shall, at least 60 days prior to the Redemption Date fixed by the
Company (unless a shorter notice shall be satisfactory to the Trustee), notify
the Trustee of such Redemption Date and of the principal amount of Securities of
such series to be redeemed and shall deliver to the Trustee such documentation
and records as shall enable the Trustee to select the Securities to be redeemed
pursuant to Section 11.03. In the case of any redemption of Securities prior to
the expiration of any restriction on such redemption provided in the terms of
such Securities or elsewhere in this Indenture, the Company shall furnish the
Trustee with an Officers' Certificate evidencing compliance with such
restriction.

SECTION 11.03. SELECTION BY TRUSTEE OF SECURITIES TO BE REDEEMED

         If less than all the Securities of any series are to be redeemed, the
particular Securities to be redeemed shall be selected not more than 60 days
prior to the Redemption Date by the Trustee, from the outstanding Securities of
such series not previously called for redemption, by such method as may be
specified by the terms of such Securities or, if no such method is so specified,
by such method as the Trustee shall deem fair and appropriate and which may
provide for the selection for redemption of portions of the principal amount of
Securities of such series.

         The Trustee shall promptly notify the Company in writing of the
Securities selected for redemption and, in the case of any Securities selected
for partial redemption, the principal amount thereof to be redeemed.

         For all purposes of this Indenture, unless the context otherwise
requires, all provisions relating to the redemption of Securities shall relate,
in the case of any Securities redeemed or to be redeemed only in part, to the
portion of the principal amount of such Securities which has been or is to be
redeemed.

SECTION 11.04. NOTICE OF REDEMPTION

         Notice of redemption shall be given by the Company or, at the Company's
request, by the Trustee to the Holders of the Securities to be redeemed, by
first-class mail, postage prepaid, mailed not less than 30 nor more than 60 days
prior to the Redemption Date, to each Holder of Securities to be redeemed, at
such Holder's address appearing in the Securities Register.

          All notices of redemption shall state:

                   (1) the Redemption Date;

                   (2) the Redemption Price;



                                      -47-
<PAGE>   54

                   (3) if less than all the Outstanding Securities of any series
are to be redeemed, the identification (and, in the case of partial redemption,
the principal amounts) of the particular Securities to be redeemed;

                   (4) that on the Redemption Date the Redemption Price will
become due and payable upon each such Security to be redeemed and, if
applicable, that interest thereon will cease to accrue on and after said date;

                   (5) the place or places where such Securities are to be 
surrendered for payment of the Redemption Price; and

                   (6) that the redemption is for a sinking fund, if such is the
case.

SECTION 11.05. DEPOSIT OF REDEMPTION PRICE

         on or before any Redemption Date, the Company shall deposit with the
Trustee or with a Paying Agent (or, if the Company is acting as its own Paying
Agent, segregate and hold in trust as provided in Section 10.03) an amount of
money sufficient to pay the Redemption Price of, and (except if the Redemption
Date shall be an Interest Payment Date) accrued interest on, all the Securities
which are to be redeemed on that date.

SECTION 11.06. SECURITIES PAYABLE ON REDEMPTION DATE

         Notice of redemption having been given as aforesaid, the Securities so
to be redeemed shall, on the Redemption Date, become due and payable at the
Redemption Price and at the place or places therein specified, and from and
after such date (unless the Company shall default in the payment of the
Redemption Price and accrued interest, if any) such Securities shall cease to
bear interest. Upon surrender of any such Security for redemption in accordance
with said notice, such Security shall be paid by the Company at the Redemption
Price, together with accrued interest to the Redemption Date; provided, however,
that installments of interest whose Stated Maturity in on or prior to the
Redemption Date shall be payable to the Holders of such Securities, or one or
more Predecessor Securities, registered as such at the close of business on the
relevant Record Dates according to their terms and the provisions of Section
3.07.

         If any Security called for redemption shall not be so paid upon
surrender therefor, the Redemption Price shall, until paid, bear interest from
the Redemption Date at the rate prescribed therefor in the Security.

SECTION 11.07. SECURITIES REDEEMED IN PART

         Any Security that is to be redeemed only in part shall be surrendered
at the place of payment therefor (with, if the Company or the Trustee so
requires, due endorsement by, or a written instrument of transfer in form
satisfactory to, the Company and the Trustee duly executed by, the Holder
thereof or his attorney duly authorized in writing), and the Company shall
execute, and the Trustee shall authenticate and deliver to the Holder of such
Security without 



                                      -48-
<PAGE>   55

service charge, a new Security or Securities of the same series, of any
authorized denomination as requested by such Holder, in aggregate principal
amount equal to and in exchange for the unredeemed portion of the principal of
the Security so surrendered.


                         ARTICLE TWELVE - SINKING FUNDS

SECTION 12.01. APPLICABILITY OF ARTICLE

         The provisions of this Article Twelve shall be applicable to any
sinking fund for the retirement of Securities of a series except as otherwise
contemplated by Section 3.01 for Securities of such series.

         The minimum amount of any sinking fund payment provided for by the
terms of Securities of any series is herein referred to as a "mandatory sinking
fund payment," and any payment in excess of such minimum amount provided for by
the terms of Securities of any series is herein referred to as an "optional
sinking fund payment." If provided for by the terms of Securities of any series,
the cash amount of any sinking fund payment may be subject to reduction as
provided in Section 12.02. Each sinking fund payment shall be applied to the
redemption of Securities of any series as provided for by the terms of
Securities of such series.

SECTION 12.02. SATISFACTION OF SINKING FUND PAYMENTS WITH SECURITIES

         The Company may (i) deliver to the Trustee Outstanding Securities of a
series (other than any previously called for redemption) theretofore purchased
or otherwise acquired by the Company and (ii) receive credit for securities of a
series which have been previously delivered to the Trustee by the Company or for
Securities of a series which have been redeemed either at the election of the
Company pursuant to the terms of such Securities or through the application of
permitted optional sinking fund payments pursuant to the terms of such
Securities, in each case in satisfaction of all or any part of any sinking fund
payment with respect to the Securities of the same series required to be made
pursuant to the terms of such Securities as provided for by the terms of such
series, provided, that such Securities have not been previously so credited.
Such Securities shall be received and credited for such purpose by the Trustee
at the Redemption Price specified in such Securities for redemption through
operation of the sinking fund and the amount of such sinking fund payment shall
be reduced accordingly.

SECTION 12.03. REDEMPTION OF SECURITIES FOR SINKING FUND

         Not less than 60 days prior to each sinking fund payment date for any
series of Securities, the Company will deliver to the Trustee an Officers,
Certificate specifying the amount of the next ensuing sinking fund payment for
that series pursuant to the terms of that series, the portion thereof, if any,
which is to be satisfied by payment of cash and the portion thereof, if any,
which is to be satisfied by delivering or crediting Securities of that series
pursuant to Section 12.02 (which Securities will, if not previously delivered,
accompany such certificate) and whether the Company intends to exercise its
right to make a permitted optional sinking fund payment with 



                                      -49-
<PAGE>   56

respect to such series. Such certificate shall be irrevocable and upon its
delivery the Company shall be obligated to make the cash payment or payments
therein referred to, if any, on or before the next succeeding sinking fund
payment date. In the case of the failure of the Company to deliver such
certificate, the sinking fund payment due on the next succeeding sinking fund
payment date for that series shall be paid entirely in cash and shall be
sufficient to redeem the principal amount of such Securities subject to a
mandatory sinking fund payment without the option to deliver or credit
Securities of such series as provided in Section 12.02 and without the right to
make any optional sinking fund payment, if any, with respect to such series.

         Not more than 60 days before each such sinking fund payment date, the
Trustee shall select the Securities of such series to be redeemed upon such
sinking fund payment date in the manner specified in Section 11.03 and cause
notice of the redemption thereof to be given in the name of and at the expense
of the Company in the manner provided in Section 11.04. Such notice having been
duly given, the redemption of such Securities shall be made upon the terms and
in the manner stated in Sections 11.06 and 11.07.

         On or prior to any sinking fund payment date, the Company shall pay to
the Trustee in cash a sum equal to any interest accrued to the date fixed for
redemption of Securities or portions thereof to be redeemed on such sinking fund
payment date pursuant to this Section 12.03.

         This instrument may be executed in any number of counterparts, each of
which when so executed shall be deemed to be an original, but all such
counterparts shall together constitute but one and the same instrument.





                                      -50-
<PAGE>   57



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

                                 EL PASO NATURAL GAS COMPANY


                                 By:     /s/ Francis J. Boyle               
                                    -------------------------------------------

Attest:

By: /s/ Eldon J. Mitrisin              
   -------------------------
                                 CITIBANK, N.A.


                                 By:     /s/ P. DeFelice                    
                                    -------------------------------------------

Attest:

By: /s/ Pam J. Cote            
   -------------------------




                                      -51-
<PAGE>   58






STATE OF NEW YORK    )
                     )
COUNTY OF NEW YORK   )

         On the 16th day of January, 1992, before me personally came Francis J.
Boyle to me known, who being by me duly sworn, did depose and say that he
resides at El Paso, Texas, that he is the Senior Vice President and Chief
Financial Officer of EL PASO NATURAL GAS COMPANY, one of the corporations
described in and which executed the foregoing instrument, and that he signed his
name thereto by like authority.


                                              /s/ Olive M. Hibbert            
                                             -----------------------------------
                                                Notary Public in and for the 
                                                       State of Texas






STATE OF NEW YORK    )
                     )       
COUNTY OF NEW YORK   )

         On the 15TH day of January, 1992, before me personally came P. DeFelice
to me known, who being by me duly sworn, did depose and say that he resides at
4709 100th Street, Flushing, N. Y. 11358; that he is an Vice President of
CITIBANK, N.A., one of the corporations described in and which executed the
foregoing instrument, and that he signed his name thereto by like authority.

                                              /s/ Nancy H. Forte            
                                             -----------------------------------
                                                       Notary Public