Document:

<PAGE>   1

                                                                     EXHIBIT 4.2

                            KIEWIT MATERIALS COMPANY

                                      AND

                           UMB BANK, N.A., AS TRUSTEE

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

                                   INDENTURE

                         DATED AS OF             , 2000

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

                            KIEWIT MATERIALS COMPANY
<PAGE>   2

     Reconciliation and tie between Trust Indenture Act of 1939 and Indenture,
dated as of             , 2000*

<TABLE>
<CAPTION>
TRUST INDENTURE
ACT SECTION                                                   INDENTURE SECTION
---------------                                               -----------------
<S>                                                           <C>
sec.310(a)(1)...............................................  6.8
     (a)(2).................................................  6.9
     (a)(3).................................................  Not Applicable
     (a)(4).................................................  Not Applicable
     (b)....................................................  6.7
                                                              6.9
sec.311(a)..................................................  6.12(a)
     (b)....................................................  6.12(b)
     (b)(2).................................................  7.3(a)(2)
                                                              7.3(b)
sec.312(a)..................................................  7.1
                                                              7.2(a)
     (b)....................................................  7.2(b)
     (c)....................................................  7.2(c)
sec.313(a)..................................................  7.3(a)
     (b)....................................................  7.3(b)
     (c)....................................................  7.3(a), 7.3(b)
     (d)....................................................  7.3(c)
sec.314(a)..................................................  7.4
     (b)....................................................  Not Applicable
     (c)(1).................................................  1.2
     (c)(2).................................................  1.2
     (c)(3).................................................  Not Applicable
     (d)....................................................  Not Applicable
     (e)....................................................  1.2
sec.315(a)..................................................  6.1(a)
     (b)....................................................  6.2
                                                              7.3(a)(6)
     (c)....................................................  6.1(b)
     (d)....................................................  6.1(c)
     (d)(1).................................................  6.1(a)(1)
     (d)(2).................................................  6.1(c)(2)
     (d)(3).................................................  6.1(c)(3)
     (e)....................................................  5.12
sec.316(a)(1)(A)............................................  5.2
                                                              5.10
     (a)(1)(B)..............................................  5.11
     (a)(2).................................................  Not Applicable
     (b)....................................................  5.8
sec.317(a)(1)...............................................  5.3
     (a)(2).................................................  5.4
     (b)....................................................  9.2
sec.318(a)..................................................  1.6
</TABLE>

---------------
* This reconciliation and tie shall not, for any purpose, be deemed to be a part
  of the Indenture.
<PAGE>   3

                               TABLE OF CONTENTS*

                                   ARTICLE I

            DEFINITIONS AND OTHER PROVISIONS OF GENERAL APPLICATION

<TABLE>
<S>            <C>                                                           <C>
Section 1.1.   Definitions.................................................    1
Section 1.2.   Compliance Certificates and Opinions........................    6
Section 1.3.   Acts of Holders.............................................    6
Section 1.4.   Notices, Etc., to Trustee and Company.......................    7
Section 1.5.   Notice to Holders; Waiver...................................    7
Section 1.6.   Conflict with Trust Indenture Act...........................    7
Section 1.7.   Effect of Headings and Table of Contents....................    7
Section 1.8.   Successors and Assigns......................................    8
Section 1.9.   Separability Clause.........................................    8
Section 1.10.  Benefits of Indenture.......................................    8
Section 1.11.  Governing Law...............................................    8
Section 1.12.  Legal Holidays..............................................    8
</TABLE>

                                   ARTICLE II

                                 SECURITY FORMS

<TABLE>
<S>            <C>                                                           <C>
Section 2.1.   Forms Generally.............................................    8
Section 2.2.   Form of Security............................................    9
Section 2.3.   Form of Trustee's Certificate of Authentication.............   11
Section 2.4.   Form of Conversion Notice...................................   11
Section 2.5.   Form of Legend on Face of Security..........................   11
</TABLE>

                                  ARTICLE III

                                 THE SECURITIES

<TABLE>
<S>            <C>                                                           <C>
Section 3.1.   Amount Unlimited; Issuable in Series........................   11
Section 3.2.   Denominations...............................................   13
Section 3.3.   Execution, Authentication, Delivery and Dating..............   13
Section 3.4.   Transfer Restrictions.......................................   13
Section 3.5.   Registration and Registration of Transfer...................   14
Section 3.6.   Payment of Interest; Interest Rights Preserved..............   14
Section 3.7.   Persons Deemed Owners.......................................   14
Section 3.8.   Cancellation................................................   14
Section 3.9.   Computation of Interest.....................................   14
</TABLE>

                                   ARTICLE IV

                           SATISFACTION AND DISCHARGE

<TABLE>
<S>            <C>                                                           <C>
Section 4.1.   Satisfaction and Discharge of Indenture.....................   15
Section 4.2.   Application of Trust Money..................................   15
</TABLE>

---------------
* This table of contents shall not, for any purpose, be deemed to be a part of
  the Indenture.

                                        i
<PAGE>   4

                                   ARTICLE V

                                    REMEDIES

<TABLE>
<S>            <C>                                                           <C>
Section 5.1.   Events of Default...........................................   16
Section 5.2.   Acceleration of Maturity; Rescission and Annulment..........   16
Section 5.3.   Collection of Indebtedness and Suits for Enforcement by        16
               Trustee.....................................................
Section 5.4.   Trustee May File Proofs of Claim............................   17
Section 5.5.   Trustee May Enforce Claims Without Possession of               17
               Securities..................................................
Section 5.6.   Application of Money Collected..............................   18
Section 5.7.   Limitation on Suits.........................................   18
Section 5.8.   Unconditional Right of Holders to Receive Principal and        18
               Interest and to Convert.....................................
Section 5.9.   Restoration of Rights and Remedies..........................   18
Section 5.10.  Control by Holders..........................................   19
Section 5.11.  Waiver of Past Defaults.....................................   19
Section 5.12.  Undertaking for Costs.......................................   19
</TABLE>

                                   ARTICLE VI

                                  THE TRUSTEE

<TABLE>
<S>            <C>                                                           <C>
Section 6.1.   Certain Duties and Responsibilities.........................   19
Section 6.2.   Notice of Defaults..........................................   20
Section 6.3.   Certain Rights of Trustee...................................   20
Section 6.4.   Not Responsible for Recitals or Issuance of Securities......   21
Section 6.5.   Money Held in Trust.........................................   21
Section 6.6.   Compensation................................................   21
Section 6.7.   Disqualification; Conflicting Interest......................   21
Section 6.8.   Corporate Trustee Required; Eligibility.....................   25
Section 6.9.   Resignation and Removal; Appointment of Successor...........   25
Section 6.10.  Acceptance of Appointment by Successor......................   26
Section 6.11.  Merger, Conversion, Consolidation or Succession to             27
               Business....................................................
Section 6.12.  Preferential Collection of Claims Against Company...........   27
</TABLE>

                                  ARTICLE VII

               HOLDERS' LISTS AND REPORTS BY TRUSTEE AND COMPANY

<TABLE>
<S>            <C>                                                           <C>
Section 7.1.   Company to Furnish Trustee Names and Addresses of Holders...   29
Section 7.2.   Preservation of Information; Communications to Holders......   30
Section 7.3.   Reports by Trustee..........................................   30
Section 7.4.   Reports by Company..........................................   31
</TABLE>

                                       ii
<PAGE>   5

                                  ARTICLE VIII

                            SUPPLEMENTAL INDENTURES

<TABLE>
<S>            <C>                                                           <C>
Section 8.1.   Supplemental Indentures Without Consent of Holders..........   32
Section 8.2.   Supplemental Indentures with Consent of Holders.............   32
Section 8.3.   Execution of Supplemental Indentures........................   33
Section 8.4.   Effect of Supplemental Indentures...........................   33
Section 8.5.   Conformity with Trust Indenture Act.........................   33
Section 8.6.   Reference in Securities to Supplemental Indentures..........   33
</TABLE>

                                   ARTICLE IX

                                   COVENANTS

<TABLE>
<S>            <C>                                                           <C>
Section 9.1.   Payment of Principal and Interest...........................   34
Section 9.2.   Money for Securities Payments to Be Held in Trust...........   34
Section 9.3.   Notice of a Change of Control...............................   35
</TABLE>

                                   ARTICLE X

                            REDEMPTION OF SECURITIES

<TABLE>
<S>            <C>                                                           <C>
Section 10.1.  Applicability of Article....................................   35
Section 10.2.  Election to Redeem..........................................   35
Section 10.3.  Notice of Redemption........................................   35
Section 10.4.  Deposit of Redemption Price.................................   35
Section 10.5.  Securities Payable on Redemption Date.......................   35
</TABLE>

                                   ARTICLE XI

                            CONVERSION OF SECURITIES

<TABLE>
<S>            <C>                                                           <C>
Section 11.1.  Right of Conversion.........................................   36
Section 11.2.  Issuance of Common Stock; Time of Conversion................   36
Section 11.3.  Adjustments in Respect of Interest..........................   36
Section 11.4.  Adjustment of Conversion Rate...............................   36
Section 11.5.  No Fractional Shares........................................   39
Section 11.6.  Trustee Not Liable..........................................   40
</TABLE>

                                  ARTICLE XII

                             PRIORITY OF SECURITIES

<TABLE>
<S>            <C>                                                           <C>
Section 12.1.  Parity With All Unsecured Indebtedness......................   40
Section 12.2.  Payment Over of Proceeds Upon Dissolution, Etc..............   40
Section 12.3.  Reliance on Judicial Order or Certificate of Liquidating       41
               Agent.......................................................
</TABLE>

                                       iii
<PAGE>   6

     INDENTURE, dated as of             , 2000, between UNITED METRO MATERIALS
INC., a corporation duly organized and existing under the laws of the State of
Delaware (the "Company"), having its principal office at Kiewit Plaza, Omaha,
Nebraska 68131, and UMB BANK, N.A., a national banking association duly
organized and existing under the laws of the United States of America, having
its Corporate Trust Office at             , Kansas City, Missouri, as 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 (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, in accordance with its terms, have been done.

     NOW, THEREFORE, THIS INDENTURE WITNESSETH:

     For and in consideration of the premises and the purchase of the Securities
by the Holders thereof, it is mutually covenanted and agreed, for the equal and
proportionate benefit of all Holders of the Securities or of series thereof, as
follows:

                                   ARTICLE I.

                        DEFINITIONS AND OTHER PROVISIONS
                             OF GENERAL APPLICATION

     Section 1.1. Definitions.

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

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

          (2) all other terms used herein which are defined in the Trust
     Indenture Act, either directly or by reference therein, have the meanings
     assigned to them therein;

          (3) 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 such computation; and

          (4) 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 that
Article.

     "Act", when used with respect to any Holder, has the meaning specified in
Section 1.3.

     "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.

     "Average Closing Market Price" means, with respect to any day:

          (a) if the Company has not terminated its obligation under its
     certificate of incorporation to repurchase shares of Common Stock, the
     Formula Price as of such day; or
<PAGE>   7

          (b) if the Company has terminated its obligation under its certificate
     of incorporation to repurchase shares of Common Stock, the average of the
     Common Stock Per Share Prices for the 10 Trading Day period ending on the
     third Trading Day prior to such day, appropriately adjusted to take into
     account the occurrence during the period commencing on the first of such
     Trading Days during such 10 Trading Day period and ending on such day any
     event that would result in an adjustment of the Conversion Rate.

     "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", when used with respect to any Place of Payment, means each
Monday, Tuesday, Wednesday, Thursday and Friday which is not a day on which
banking institutions in that Place of Payment are authorized or obligated by law
to close.

     "Change of Control" means the occurrence, after the date hereof, of any of
the following:

          (a) any Person (including any syndicate or group deemed to be a
     "person" under Section 13(d)(3) of the Securities Exchange Act of 1934),
     other than the Company, any Subsidiary of the Company, any employee benefit
     plan of the Company or any such Subsidiary becomes the beneficial owner,
     directly or indirectly, through a purchase or other acquisition transaction
     or series of transactions (other than a merger or consolidation involving
     the Company), of shares of capital stock of the Company entitling such
     Person to exercise in excess of 50% of the total voting power of all shares
     of capital stock of the Company entitled to vote generally in the election
     of directors;

          (b) any consolidation of the Company with, or merger of the Company
     into, any other Person, any merger of another Person into the Company, or
     any sale or transfer of the assets of the Company as, or substantially as,
     an entirety, to another Person (other than (i) any such transaction
     pursuant to which the holders of the Voting Stock immediately prior to such
     transaction have, directly or indirectly, shares of capital stock of the
     continuing or surviving corporation immediately after such transaction
     which entitle such holders to exercise in excess of 50% of the total voting
     power of all shares of capital stock of the continuing or surviving
     corporation entitled to vote generally in the election of directors and
     (ii) any merger (A) which does not result in any reclassification,
     conversion, exchange or cancellation of outstanding shares of Voting Stock
     or (B) which is effected solely to change the jurisdiction of incorporation
     of the Company and results in a reclassification, conversion or exchange of
     outstanding shares of Voting Stock solely into shares of stock carrying
     substantially the same relative rights as the Voting Stock); or

          (c) a change in the Board of Directors of the Company in which the
     individuals who constituted the Board of Directors of the Company at the
     beginning of the two-year period immediately preceding such change
     (together with any other directors whose election to the Board of Directors
     of the Company or whose nomination for election by the stockholders of the
     Company was approved by a vote of at least a majority of the directors then
     in office either who were directors at the beginning of such period or
     whose election or nomination for election was previously so approved) cease
     for any reason to constitute a majority of the directors then in office in
     the event the Company has terminated its obligation under its certificate
     of incorporation to repurchase shares of Common Stock.

     "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.

     "Common Stock" means (i) the class of common stock issued by the Company
which is designated "Common Stock", which has general voting rights, which has
no preference in respect of dividends or of amounts payable in the event of any
voluntary or involuntary liquidation, dissolution or winding up the

                                        2
<PAGE>   8

Company and which is not subject to redemption by the Company, or (ii) any other
class of common stock issued by the Company which is designated in a Board
Resolution or supplemental indenture establishing the terms of a series of
Securities pursuant to Section 3.1 as the class of stock into which the
Securities of such series shall be convertible.

     "Common Stock Per Share Price" means, with respect to any day,

          (a) if the Company has not terminated its obligation under its
     certificate of incorporation to repurchase shares of Common Stock, the
     Formula Price; or

          (b) if the Company has terminated its obligation under its certificate
     of incorporation to repurchase shares of Common Stock, the closing sale
     price regular way on such day or, in case no such sale takes place on such
     day, the average of the reported closing bid and asked prices, regular way,
     on such day, in each case on the New York Stock Exchange, or, if such
     security is not listed or admitted to trading on such Exchange, on the
     principal national security exchange or quotation system on which such
     security is quoted or listed or admitted to trading, or, if not quoted or
     listed or admitted to trading on any national securities exchange or
     quotation system, the average of the closing bid and asked prices of such
     security on such day on the over-the-counter market on such day as reported
     by the National Quotation Bureau Incorporated, or a similar generally
     accepted reporting service, or if not so available, in such manner as
     furnished by any New York Stock Exchange member firm selected from time to
     time by the Board of Directors for that purpose, or a price per share of
     Common Stock as of such day as determined in good faith by the Board of
     Directors or, to the extent permitted by applicable law, a duly authorized
     committee thereof, whose determination shall be conclusive.

     "Company" means the Person named as the "Company" in the first paragraph of
this instrument and its successors and assigns.

     "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 or
a Vice President, and by its Treasurer, an Assistant Treasurer its Secretary or
an Assistant Secretary, and delivered to the Trustee.

     "Conversion Date" has the meaning set forth in Section 11.2.

     "Conversion Interest Termination Date" means, with respect to any Security:

          (i) June 30 of the Regular Conversion Year applicable to such Security
     if such Security is converted into Common Stock during the Regular
     Conversion Period applicable to such Security; and

          (ii) the Conversion Date if such Security is converted into Common
     Stock during a Special Conversion Period applicable to such Security.

     "Conversion Period" means, with respect to any Security, the Regular
Conversion Period and any Special Conversion Period applicable to such Security.

     "Corporate Trust Office" means the office of the Trustee in Kansas City,
Missouri at which at any particular time its corporate trust business shall be
principally administered, and which at the date hereof is located at
               .

     "Corporation" includes corporations, associations, companies, joint-stock
companies and business trusts.

     "Debenture Repurchase Agreement" means each agreement between a Holder and
the Company, in substantially the Form of Exhibit A.

                                        3
<PAGE>   9

     "Event of Default" has the meaning specified in Section 5.1.

     "Formula Price" means, with respect to any day:

          (a) the total stockholders' equity as shown on the consolidated
     balance sheet contained in the consolidated financial statements of the
     Company consolidated subsidiaries, prepared in conformity with generally
     accepted accounting principles applied on a consistent basis for the
     Company and its consolidated subsidiaries as of the prior year end and
     audited and certified by an independent firm of certified public
     accountants selected and engaged by the Board of Directors; minus

          (b) the sum of (i) such total stockholders' equity attributable to any
     issued and outstanding preferred stock, plus (ii) the amount of any
     accrued, accumulated and undeclared dividends on such preferred stock, all
     as of the date of determination; divided by

          (c) the number of shares of Common Stock outstanding on the date of
     determination.

     "Holder" means a Person in whose name a Security is registered in the
Security 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 and shall
include the terms of particular series of Securities established as contemplated
by Section 3.1.

     "Interest Payment Date", when used with respect to any Security, means the
Stated Maturity of an installment of interest on such Security.

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

     "Officers' Certificate" means a certificate signed by the Chairman of the
Board, the President 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.

     "Opinion of Counsel" means a written opinion of counsel, who may be counsel
to the Company, and who shall be acceptable to the Trustee.

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

          (a) Any such Securities theretofore cancelled by the Trustee or
     delivered to the Trustee for cancellation;

          (b) Any such Securities for whose payment or redemption 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; provided that, if such Securities are
     to be redeemed, notice of such redemption has been duly given pursuant to
     this Indenture or provision therefor satisfactory to the Trustee has been
     made; and

          (c) Any such Securities in lieu of which other Securities have been
     authenticated and delivered pursuant to this Indenture, other than any such
     Securities in respect of which there shall have been presented to the
     Trustee proof satisfactory to it that such Securities are held by a bona
     fide purchaser in whose hands such Securities are valid obligations of the
     Company;

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

                                        4
<PAGE>   10

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 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, limited liability
company, joint venture, trust, unincorporated organization or government or any
agency or political subdivision thereof.

     "Place of Payment", when used with respect to the Securities of any series,
means the principal office of the Company in Omaha, Nebraska and such other
place or places where principal of and interest on the Securities of that series
are payable as specified in a Board Resolution or supplemental indenture
establishing the terms of such series pursuant to Section 3.1.

     "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 pursuant to this Indenture.

     "Regular Conversion Period" means, with respect to any series of
Securities, the period beginning on October 1 and ending on October 31 in the
year which is five years after the date of issuance of such series of Securities
or any other period specified in a Board Resolution or supplemental indenture
establishing the terms of such series pursuant to Section 3.1.

     "Regular Conversion Year" means, with respect to any series of Securities,
the year which is five years after the date of issuance of such series of
Securities or any other period specified in a Board Resolution or supplemental
indenture establishing the terms of such series pursuant to Section 3.1.

     "Regular Record Date" for the interest payable on any Interest Payment Date
on the Securities of any series means the date specified for that purpose as
contemplated by Section 3.1.

     "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.

     "Security Register" and "Security Registrar" have the respective meanings
specified in Section 3.5.

     "Special Conversion Period" means, with respect to any Security, any of the
following periods commencing prior to the commencement of the Regular Conversion
Period:

          (1) the thirty (30) day period immediately following the death of the
     Holder of such Security;

          (2) the thirty (30) day period immediately following a Change of
     Control; or

          (3) the thirty (30) day period immediately prior to the Redemption
     Date.

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

                                        5
<PAGE>   11

     "Subsidiary" means any Corporation in which the Company owns directly or
indirectly at least 20 percent of the outstanding capital stock, based on the
total dollar value of outstanding stock if there is more than one class of stock
outstanding.

     "Trading Day" means (x) if the applicable security is listed or admitted
for trading on the New York Stock Exchange, the Nasdaq National Market or
another national security exchange, a day on which the New York Stock Exchange,
the Nasdaq National Market or another national security exchange is open for
business or (y) if the applicable security is quoted on the Nasdaq National
Market, a day on which trades may be made thereon or (z) if the applicable
security is not so listed, admitted for trading or quoted, any day other than a
Saturday or Sunday or a day on which banking institutions in the State of New
York are authorized or obligated by law or executive order to close.

     "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
each Person who is then a Trustee hereunder, and if at any time there is more
than one such Person, "Trustee" as used with respect to the Securities of any
series shall mean the Trustee with respect to Securities of that series.

     "Trust Indenture Act" means the Trust Indenture Act of 1939 as in force at
the date as of which this instrument was executed, except as provided in Section
8.5.

     "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 the Common Stock and any other stock of the Company
which votes together with the Common Stock in the election of directors (without
regard to whether there has been an arrearage in the payment of dividends on
preferred stock).

     Section 1.2. 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.

     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 or not 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 1.3. 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 may
be embodied in and evidenced by one or more instruments of substantially similar
tenor signed by such Holders in person or by an agent duly appointed in writing;
and, except as herein otherwise expressly provided, such action shall become
effective when such instrument or
                                        6
<PAGE>   12

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 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 6.1)
conclusive in favor of the Trustee and the Company, if made in the manner
provided in this Section.

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

     (c) 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
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 1.4. 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,

          (1) 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, or

          (2) 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 instrument, Attention: President, or at any other
     address previously furnished in writing to the Trustee by the Company.

     Section 1.5. Notice 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 Security 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 such notice by mail, then such
notification as shall be made with the approval of the Trustee shall constitute
a sufficient notification for every purpose hereunder.

     Section 1.6. 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.

     Section 1.7. Effect of Headings and Table of Contents.

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

                                        7
<PAGE>   13

     Section 1.8. Successors and Assigns.

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

     Section 1.9. 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 1.10. 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, any benefit or any legal or equitable right, remedy or claim
under this Indenture.

     Section 1.11. Governing Law.

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

     Section 1.12. Legal Holidays.

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

                                  ARTICLE II.

                                 SECURITY FORMS

     Section 2.1. Forms Generally.

     The Securities of each series shall be in substantially the form set forth
in this Article, or in such other form as shall be established by or pursuant to
a Board Resolution 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 such
letters, numbers or other marks of identification and such legends or
endorsements placed thereon as may, consistently herewith, be determined by the
officers executing such Securities, as evidenced by their execution of such
Securities. If the form of Securities of any series is established by action
taken pursuant to a Board Resolution, a copy of an 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 3.3 for the authentication and delivery of such
Securities.

     The Trustee's certificates of authentication shall be in substantially the
form set forth in this Article.

     The legend appearing on the face of the Securities shall be in
substantially the form set forth in this Article.

     The definitive Securities shall be typed, printed, lithographed or
engraved, or produced by any combination of these methods, all as determined by
the officers executing such Securities, as evidenced by their execution of such
Securities.

                                        8
<PAGE>   14

     Section 2.2. Form of Security.

                         FORM OF CONVERTIBLE DEBENTURE
                            KIEWIT MATERIALS COMPANY
                             A DELAWARE CORPORATION

Registered Debenture No.                                $
     % Convertible Debenture                               Due: October 31, 2

     KIEWIT MATERIALS COMPANY, a corporation organized and existing under the
laws of the State of Delaware, and having its principal place of business in the
City of Omaha, Nebraska (hereinafter called the "Corporation"), for the value
received, hereby promises to pay to                or registered assigns
(hereinafter called the "Debentureholder") on October 31, 2   , the principal
sum of                ($          ) Dollars.

     This debenture is one of the        series of registered convertible
debentures of the Corporation, due October 31, 2   unless previously redeemed or
converted, limited to the aggregate principal amount of                and
No/100 ($          ) Dollars, all issued or to be issued pursuant to an
indenture, dated as of             , 2000 (the "Indenture"), executed and
delivered by the Corporation and UMB Bank, N.A. as Trustee, (hereinafter
referred to as "Trustee"). This debenture is subject to the terms of the
Indenture, and all indentures supplemental thereto, and reference is hereby made
to the Indenture and any such supplemental indenture for a description of the
rights, limitations, obligations and immunities of the Corporation, the holders
of the debentures and the Trustee. Capitalized terms used and not defined herein
have the meanings ascribed to those terms in the Indenture.

     (1) TYPE OF PAYMENT:  Payment of interest and principal shall be in any
coin or currency of the United States of America which at the time of payment
shall be legal tender for the payment of public or private debts.

     (2) INTEREST:  Except as hereinafter provided, the Corporation promises to
pay to the registered holder hereof or his registered assigns, interest on the
principal sum of this debenture at the rate of      % per annum until the
Corporation's obligation with respect to the payment of the principal amount
shall have been discharged. Interest shall accrue upon this debenture from the
most recent date to which interest has been paid, or if no interest has been
paid, from the date of original issuance. In the event of conversion as provided
in paragraph (7)(a) hereof, interest shall cease accruing on the principal
amount of this debenture on June 30, 2   . In the event of conversion as
provided in paragraph (7)(b) hereof, interest shall cease accruing on the
principal amount of this debenture on the Conversion Date. Interest on this
debenture shall be paid annually on each November 1st, commencing November 1,
2   .

     (3) PLACE OF PAYMENT:  The principal and interest on this debenture shall
be payable at the office of the Corporation in Omaha, Nebraska.

     (4) DEFAULT:  This debenture shall be deemed to be in default whenever the
principal sum and/or interest becomes payable and remains unpaid for a period of
sixty (60) days.

     (5) REDEMPTION:  This debenture is subject to redemption at any time prior
to the date of maturity at its principal amount plus all accrued and unpaid
interest to the date of redemption, provided, however, that the entire series is
redeemed. This debenture may not be redeemed during the thirty-one (31) day
conversion period provided for in paragraph (7)(a) hereof. Redemption shall be
preceded by notice thereof, mailed to the registered holder by registered mail
no later than thirty (30) days preceding the date of redemption. The registered
holder may convert this debenture into Common Stock during that thirty (30) day
period preceding the date set for redemption as provided for in paragraph 7(b)
hereof.

     (6) TRANSFER:  The debenture may be transferred by the registered holder at
the principal office of the Corporation in Omaha, Nebraska on registry books
kept for such purpose at such office, upon surrender and

                                        9
<PAGE>   15

cancellation of this debenture, and the payment of applicable charges. The
Corporation and the Trustee may treat the registered holder of this debenture as
the absolute owner for all purposes.

     (7) CONVERSION:

     (a) This debenture is convertible into the $0.01 par value common stock
("Common Stock") of the Corporation on the following basis: during the period
commencing on October 1, 2   and ending on October 31, 2   , the registered
holder may convert the entire principal amount of this debenture, plus a cash
payment equal to the product of                multiplied by the Average Closing
Market Price on the Conversion Date, into                (               )
shares of Common Stock, subject to adjustment upon the occurrence of certain
events as provided in the Indenture.

     (b) If any of the following events occur prior to October 1, 2   , this
debenture is convertible into Common Stock: (i) for thirty (30) days following
the occurrence of the registered holder's death; (ii) for thirty (30) days
following a Change of Control; and (iii) for thirty (30) days prior to
redemption of the registered holder's debentures, as provided for in paragraph
(5) hereof. During any such period, the registered holder or the registered
holder's representative or estate, as the case may be, may convert the entire
principal amount of the debenture plus a cash payment equal to the product of
               multiplied by the Average Closing Market Price on the Conversion
Date, into                (               ) shares of Common Stock, subject to
adjustment upon the occurrence of certain events as provided in the Indenture.

     (c) During the period commencing on November 1, 2   and ending on October
31, 2   , the date of maturity, the debenture is not convertible, in whole or in
part.

     (d) The conversion privilege shall be deemed exercised by submission of
this debenture with a written request for conversion plus the required cash
payment during the applicable conversion period at the principal office of the
Corporation. The Corporation shall thereafter, within a sixty (60) day period,
issue certificates registered in the name of the registered holder representing
the shares of Common Stock into which this debenture has been converted.

     (8) SUBORDINATION:  In the payment of their claims, all creditors of the
Corporation shall rank equally with the holders of convertible debentures. All
claims of the debentureholders against earnings or assets are hereby made
superior to those of stockholders, and the Corporation agrees that as long as
any of its convertible debentures are outstanding, it will not pay any dividends
on its stock until all liability for unpaid interest on its debentures has been
paid. In the event of dissolution or liquidation of the Corporation, the holders
of all debentures shall be entitled to be paid in full, both principal and
interest, before any assets of the Corporation are distributed to any
stockholder.

     (9) LIQUIDATION OF LIABILITY:  No recourse shall be had for the payment of
the principal or interest of this debenture, against any incorporator,
stockholder, officer, or director, past, present, or future, of the Corporation,
all such liability being expressly waived by the owner of this debenture.

     (10) VALIDATION:  This debenture shall not be valid or become obligatory
for any purpose until the certificate of authentication thereon shall have been
signed by the Trustee.

     IN WITNESS WHEREOF, Kiewit Materials Company has caused this debenture to
become signed and its corporate seal to be hereunto affixed by its officers duly
authorized thereunto, all as of the   day of           , 2   .

<TABLE>
<S>                                                    <C>
ATTEST:                                                KIEWIT MATERIALS COMPANY

-----------------------------------------------------  By: -------------------------------------------------
Assistant Secretary                                    President
</TABLE>

                                       10
<PAGE>   16

TRUSTEE'S CERTIFICATE OF AUTHENTICATION:  This is one of the debentures
described in the Trust Indenture, dated as of           , 2000, by and between
Kiewit Materials Company and UMB Bank, N.A. as Trustee.

<TABLE>
<S>                                                    <C>
Dated --------------------------------------------     By: -------------------------------------------------
                                                           Authorized Officer
</TABLE>

This Debenture and the transfer thereof are subject to restrictions which are
stated in an Agreement between the Debentureholder(s) whose name(s) appear(s)
hereon and KIEWIT MATERIALS COMPANY, dated           , 2   .

     Section 2.3. Form of Trustee's Certificate of Authentication.

     This is one of the debentures described in the Indenture dated as of
          , 2000, by and between the Corporation and UMB Bank, N.A., as Trustee.

     Section 2.4. Form of Conversion Notice.

                                                                          [Date]

Kiewit Materials Company
Kiewit Plaza
Omaha, Nebraska 68131

Gentlemen:

     Please accept this as written notice that the undersigned hereby elects to
     exercise his right to convert Kiewit Materials Company   % Convertible
     Debenture No.      into       shares of Kiewit Materials Company common
     stock.

     [If applicable -- By furnishing UMB Bank, N.A. with copy of this notice, I
hereby authorize it to deliver the aforementioned Debenture to you on or before
                    , 2          .]

cc: UMB Bank, N.A.

    ----------------------------------------------------------
    Kansas City, Missouri

     Section 2.5. Form of Legend on Face of Security.

     THESE DEBENTURES AND THE TRANSFER THEREOF ARE SUBJECT TO RESTRICTIONS WHICH
ARE STATED IN AN AGREEMENT ENTITLED "AGREEMENT" WITH RESPECT TO CONVERTIBLE
DEBENTURES OF KIEWIT MATERIALS COMPANY BETWEEN KIEWIT MATERIALS COMPANY. AND THE
DEBENTUREHOLDER(S) WHOSE NAME(S) APPEAR(S) ON THIS CERTIFICATE.

                                  ARTICLE III.

                                 THE SECURITIES

     Section 3.1. Amount Unlimited; Issuable in Series.

     The aggregate principal amount of Securities which may be authenticated and
delivered under this Indenture is unlimited.

                                       11
<PAGE>   17

     The Securities may be issued in one or more series. There shall be
established in or pursuant to a Board Resolution, 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:

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

          (2) any limit upon the aggregate principal amount of the Securities of
     the series which may be authenticated and delivered under this Indenture
     (except for Securities authenticated and delivered in lieu of other
     Securities of the series pursuant to Section 8.6.

          (3) the date or dates on which the principal of the Securities of the
     series is payable;

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

          (5) the place or places in addition to Omaha, Nebraska, if any, where
     the principal of and interest on Securities of the series shall be payable;

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

          (7) the Conversion Interest Termination Date, if other than (i) June
     30 of the Regular Conversion Year if the Securities are converted into
     Common Stock during the Regular Conversion Period; or (ii) the Conversion
     Date if any Security is converted into Common Stock during a Special
     Conversion Period;

          (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 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
     5.2;

          (10) additional restrictions on the ability of a Holder to transfer
     the Securities of such series, if any, other than those set forth herein;

          (11) additional Events of Default with respect to Securities of such
     series, if any, other than those set forth herein;

          (12) the rate at which Holders of Securities of the series may convert
     such Securities into shares of Common Stock of the Company pursuant to
     Article XI hereof, and the Conversion Period if other than the Regular
     Conversion Period or the Special Conversion Period;

          (13) if other than Common Stock, the class of common stock of the
     Company into which the Securities of the series are convertible; and

          (14) any other terms of the Securities of such series (which terms
     shall not be inconsistent with the provisions of this Indenture).

     All Securities of any one series shall be substantially identical except as
to denomination and except as may otherwise be provided in or pursuant to such
Board Resolution and set forth in such Officers' Certificate or in any such
indenture supplemental hereto.

     If any of the terms of the series are established by action taken pursuant
to a Board Resolution, a copy of an 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 Officers'
Certificate setting forth the terms of the series.

                                       12
<PAGE>   18

     Section 3.2. Denominations.

     The Securities of each series shall be issuable in registered form without
coupons in such denominations as shall be specified as contemplated by Section
3.1. In the absence of any such provisions 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.

     Section 3.3. Execution, Authentication, Delivery and Dating.

     The Securities shall be executed on behalf of the Company by its Chairman
of the Board, its President 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 signature of individuals who
were at the time of signature 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 the Company Order shall authenticate and deliver such Securities. If the
form or terms of the Securities of the series have been established in or
pursuant to one or, Board Resolutions as permitted by Sections 2.1 and 3.1, 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 (subject to Section 6.1) shall be fully protected in
relying upon, an Opinion of Counsel stating:

          (a) if the form of such Securities has been established by or pursuant
     to Board Resolution as permitted by Section 2.1, that such form has been
     established in conformity with the provisions of this Indenture;

          (b) if the terms of such Securities have been established by or
     pursuant to Board Resolution as permitted by Section 3.1, that such terms
     have been established in conformity with the provisions of this Indenture;
     and

          (c) that such Securities, when authenticated and delivered by the
     Trustee and issued by the Company in the manner and subject to any
     conditions specified in such Opinion of Counsel, will constitute valid and
     legally binding obligations of the Company, enforceable in accordance with
     their terms, subject to bankruptcy, insolvency, reorganization and other
     laws of general applicability relating to or affecting the enforcement of
     creditors' rights and to general equity principles.

     If such form or terms have been so established, the Trustee shall not be
required to authenticate such Securities if the issue 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 issuance.

     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 and is entitled to the
benefits of this Indenture.

     Section 3.4. Transfer Restrictions.

     Except as specifically provided in the Debenture Repurchase Agreement, the
execution of which is a condition precedent to the purchase of the Securities of
any series, no Holder shall give, sell, assign, pledge, or otherwise transfer
any Securities, by any means, whether voluntary or involuntary, except for
pledges of

                                       13
<PAGE>   19

Securities as collateral for loans in connection with the ownership of the
Securities. Any Holder may at any time sell his Securities to the Company in the
manner and in accordance with the terms specified in the Debenture Repurchase
Agreement. Upon (i) United Metro's termination of the Holder's employment with
the Company, other than as a result of the death of the Holder; or (ii) subject
to the exceptions in such Holder's Debenture Repurchase Agreement, the Holder's
death, the Holder, the Holder's representative, or the Holder's estate shall
sell all the Securities owned by the Holder to the Company and the Company shall
purchase all such Securities, all in accordance with the terms of the Debenture
Repurchase Agreement.

     Section 3.5. Registration and Registration of Transfer.

     The Company shall keep a register (the "Security Register") at its
principal office in Omaha, Nebraska in which, subject to such reasonable
regulations as it may prescribe, the Company shall provide for the registration
of Securities. The Company shall be "Security Registrar" for the purpose of
registering Securities and transfers of Securities as herein provided.

     Upon surrender for registration of transfer of any Security by the Holder
thereof pursuant to the terms of the Debenture Repurchase Agreement and the
payment of applicable charges, the Company shall register the transfer of the
Security in the Security Register. Such Security shall be cancelled by the
Company and shall no longer be deemed to be Outstanding. The Company shall not
be required to register the transfer of any Security transferred in violation of
the Debenture Repurchase Agreement.

     Every Security presented or surrendered for registration of transfer shall
be endorsed in blank or accompanied by appropriate transfer powers executed in
blank, and accompanied by such other evidence of authority as the Company may
reasonably require.

     Section 3.6. 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 at Maturity shall be paid to the
Person in whose name that Security is registered at the close of business on the
Regular Record Date for such interest.

     Interest shall cease running on the Conversion Interest Termination Date on
the principal amount of any Security which is surrendered for conversion
pursuant to Article XI hereof. If any Security is surrendered for conversion
after the close of business on any Regular Record Date and on or prior to the
next succeeding Interest Payment Date (other than any Security whose Maturity is
prior to such Interest Payment Date), interest on such Security shall be payable
on such Interest Payment Date notwithstanding such conversion, but only in an
amount equal to the interest accrued to the Conversion Interest Termination
Date, and such interest shall be paid to the Person in whose name that Security
is registered at the close of business on such Regular Record Date.

     Section 3.7. 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 interest 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 3.8. Cancellation.

     All Securities surrendered for payment, redemption, conversion or
registration of transfer shall be delivered to the Company and shall be
cancelled by it.

     Section 3.9. Computation of Interest.

     Except as otherwise specified as contemplated by Section 3.1 for Securities
of any series, interest on the Securities of each series shall be computed on
the basis of a year of 365 days.

                                       14
<PAGE>   20

                                  ARTICLE IV.

                           SATISFACTION AND DISCHARGE

     Section 4.1. Satisfaction and Discharge of Indenture.

     This Indenture shall upon Company Request cease to be in effect (except as
to any surviving rights of conversion or registration of transfer of Securities
herein expressly provided for), and the Trustee, at the expense of the Company,
shall execute proper instruments acknowledging satisfaction and discharge of
this Indenture, when

          (1) either

             (A) all Securities theretofore authenticated and delivered (other
        than Securities for whose payment money has theretofore been deposited
        in trust or segregated and held in trust by the Company and thereafter
        repaid to the Company or discharged from such trust, as provided in
        Section 9.2) have been delivered to the Trustee for cancellation; or

             (B) all such Securities not theretofore delivered to the Trustee
        for cancellation

                (i) have become due and payable, or

                (ii) will become due and payable at their Stated Maturity within
           one year, or

                (iii) are to be called for redemption within one year under
           arrangements satisfactory to the Trustee for the giving of notice of
           redemption by the Trustee in the name, and at the expense, of the
           Company and the Company, in the case of (i), (ii) or (iii) above, has
           deposited or caused to be deposited with the Trustee as trust funds
           in trust an amount sufficient to pay and discharge the entire
           indebtedness on such Securities not theretofore delivered to the
           Trustee for cancellation, for principal and interest to the date of
           such deposit (in the case of Securities which have become due and
           payable) or to the Stated Maturity or Redemption Date, as the case
           may be;

          (2) the Company has paid or caused to be paid all other sums payable
     hereunder by the Company; and

          (3) the Company has delivered to the Trustee an Officers' Certificate
     and an Opinion of Counsel, each stating that all conditions precedent
     herein provided for relating to the satisfaction and discharge of this
     Indenture have been complied with.

     Notwithstanding the satisfaction and discharge of this Indenture, the
obligations of the Company to the Trustee under Section 6.6 and, if money shall
have been deposited with the Trustee pursuant to subclause (B) of clause (1) of
this Section, the obligations of the Trustee under Section 4.2 and the last
paragraph of Section 9.2 shall survive.

     Section 4.2. Application of Trust Money.

     Subject to the provisions of the last paragraph of Section 9.2, all money
deposited with the Trustee pursuant to Section 4.1 shall be held in trust and
applied by it, in accordance with the provisions of the Securities and this
Indenture, to the payment, either directly or through any Paying Agent
(including the Company acting as its own Paying Agent) the Trustee may
determine, to the Persons entitled thereto, of the principal and interest for
whose payment such money has been deposited with the Trustee. All moneys
deposited with the Trustee pursuant to Section 4.1 (and held by it or any Paying
Agent for the payment of Securities subsequently converted shall be returned to
the Company upon receipt by the Trustee for a Company Request to such effect.

                                       15
<PAGE>   21

                                   ARTICLE V.

                                    REMEDIES

     Section 5.1. Events of Default.

     "Event of Default", wherever used herein with respect to Securities of any
series, means any one of the following events (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 any interest upon any Security of that
     series when it becomes due and payable, and continuance of such default for
     a period of 60 days; or

          (2) default in the payment of the principal of any Security of that
     series at its Maturity, and continuance of such default for a period of 60
     days; or

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

     Section 5.2. Acceleration of Maturity; Rescission and Annulment.

     If an Event of Default with respect to Securities of any series at the time
Outstanding occurs and is continuing, then in every such case the Trustee may
declare the principal amount of all of the Securities of that series to be due
and payable immediately, by a notice in writing to the Company and upon any such
declaration such principal amount shall become immediately due and payable.

     At any time after such a declaration of acceleration with respect to
Securities of any series 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 that series, 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 interest on all Securities of that series,

             (B) the principal of any Securities of that series which have
        become due otherwise than by such declaration of acceleration and
        interest thereon at the rate or rates prescribed therefor in such
        Securities, and

             (C) 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 with respect to Securities of that series,
     other than the non-payment of the principal of Securities of that series
     which have become due solely by such declaration of acceleration, have been
     cured or waived as provided in Section 5.12.

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

     Section 5.3. Collection of Indebtedness and Suits for Enforcement by
Trustee.

     The Company covenants that if

          (1) default is made in the payment of any interest on any Security
     when such interest becomes due and payable and such default continues for a
     period of 60 days, or

          (2) default is made in the payment of the principal of any Security at
     the Maturity thereof and such default continues for a period of 60 days,

the Company will, upon demand of the Trustee, pay to it, for the benefit of the
Holders of such Securities, the whole amount then due and payable on such
Securities for principal and interest, at the rate or

                                       16
<PAGE>   22

rates prescribed therefor in such Securities 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, then 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 such Securities 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 such Securities, wherever situated.

     If any Event of Default with respect to Securities of any series occurs and
is continuing, the Trustee may in its discretion proceed to protect and enforce
its rights and the rights of the Holder of Securities of such series 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 5.4. 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
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,

          (i) to file and prove a claim for the whole amount of principal and
     interest owing and unpaid in respect of the Securities and to 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

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

and any custodian, receiver, assignee, trustee, liquidator, sequestrator or
other similar official in any such judicial proceeding is hereby authorized by
each Holder to make such payments to the Trustee by such Holder's acceptance of
Securities hereunder and, in the event that the Trustee 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 6.6.

     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 5.5. 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.

                                       17
<PAGE>   23

     Section 5.6. Application of Money Collected.

     Any money collected by the Trustee pursuant to this Article 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 or interest,
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
     6.6;

          SECOND: To the payment of the amounts then due and unpaid for
     principal and interest on the Securities 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 interest, respectively; and

          THIRD: To the payment of the remainder, if any, to the Company, its
     successors or assigns, or to whoever may be lawfully entitled to receive
     the same, or as a court of competent jurisdiction may direct.

     Section 5.7. 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

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

          (2) the Holders of not less than 25% in principal amount of the
     Outstanding Securities of that series 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;

          (3) 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;

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

          (5) 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 that series;

     it being understood and intended that no one or more of such 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 of such Holders, or to obtain or to seek to obtain priority or preference
over any other of such Holders or to enforce any right under this Indenture,
except in the manner herein provided and for the equal and ratable benefit of
all of such Holders.

     Section 5.8. Unconditional Right of Holders to Receive Principal and
Interest and to Convert.

     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 and interest on such Security on the Stated Maturity or
maturities expressed in such Security (or, in the case of redemption, on the
Redemption Date) and to convert such Security in accordance with Article XI and
to institute an action for the enforcement of any such payment and right to
convert, and such rights shall not be impaired without the consent of such
Holder.

     Section 5.9. 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
                                       18
<PAGE>   24

former positions hereunder and thereafter all rights and remedies of the Trustee
and the Holders shall continue as though such proceeding had not been
instituted.

     Section 5.10. Control by Holders.

     The Holders of a majority in principal amount of the Outstanding Securities
of any series 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

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

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

     Section 5.11. Waiver of Past Defaults.

     The Holders of not less than a majority in principal amount of the
Outstanding Securities of any series 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

          (1) in the payment of the principal of or interest on any Security of
     such series, or

          (2) in respect of a covenant or provision hereof which under Article
     VIII 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 with respect to the Securities of such series; but no such
waiver shall extend to any subsequent or other default or impair any right
consequent thereon.

     Section 5.12. 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,
suffered 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 shall not apply to any suit instituted by the
Company, 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 any series, or to any suit instituted by
any Holder for the enforcement of the payment of the principal of or interest on
any Security on or after the Stated Maturity or Maturities expressed in such
Security (or, in the case of redemption, on or after the Redemption Date).

                                  ARTICLE VI.

                                  THE TRUSTEE

     Section 6.1. Certain Duties and Responsibilities.

     (a) Except during the continuance of an Event of Default,

          (1) the Trustee undertakes 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

                                       19
<PAGE>   25

     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 has occurred and is continuing, the Trustee
shall 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 man would
exercise or use under the circumstances in the conduct of his 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 Subsection shall not be construed to limit the effect of
     Subsection (a) of this Section;

          (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;

          (3) the Trustee shall not be liable with respect to any action taken
     or omitted to be taken by it in good faith in accordance with the direction
     of the Holders of a majority in principal amount of the Outstanding
     Securities of any series, determined as provided in Section 5.10, 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 with respect to the Securities of such
     series; and

          (4) 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 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.

          (d) Whether or not therein expressly so provided, every provision of
     this Indenture relating to the conduct or affecting the liability of or
     affording protection to the Trustee shall be subject to the provisions of
     this Section.

     Section 6.2. 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 Securities of such series, as their names and addresses appear in the
Security Register, 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, or interest 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 of Securities of such series. For the purpose of this Section, 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 6.3. Certain Rights of Trustee.

     Subject to the provisions of Section 6.1:

          (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, other evidence of indebtedness or other paper or
     document believed by it to be genuine and to have been signed or presented
     by the proper party or parties;

          (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

                                       20
<PAGE>   26

     (unless other evidence be herein specifically prescribed) may, in the
     absence of bad faith on its part, rely upon an Officer's 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 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, other evidence of indebtedness 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 and records of the Company,
     personally or by agent or attorney, upon ten days written notice to the
     Company of its intention to make such examination; 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 6.4. 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 6.5. 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 6.6. Compensation.

     The Company agrees to pay to the Trustee the amounts on the fee schedule
attached as Exhibit B hereto as such schedule may be amended from time to time.

     Section 6.7. Disqualification; Conflicting Interest.

     (a) If the Trustee has or shall acquire any conflicting interest, as
defined in this Section, with respect to the Securities of any series, it shall,
within 90 days after ascertaining that it has such conflicting interest, either
eliminate such conflicting interest or resign with respect to the Securities of
that series in the manner and with the effect hereinafter specified in this
Article.

     (b) In the event that the Trustee shall fail to comply with the provisions
of Subsection (a) of this Section with respect to the Securities of any series,
the Trustee shall, within 10 days after the expiration of such 90-day period,
transmit by mail to all Holders of Securities of that series, as their names and
addresses appear in the Security Register, notice of such failure.

     (c) For the purposes of this Section, the Trustee shall be deemed to have a
conflicting interest with respect to the Securities of any series if

          (1) the Trustee is trustee under this Indenture with respect to the
     Outstanding Securities of any series other than that series or is trustee
     under another indenture under which any other securities, or

                                       21
<PAGE>   27

     certificates of interest or participation in any other securities, of the
     Company are outstanding, unless such other indenture is a collateral trust
     indenture under which the only collateral consists of Securities issued
     under this Indenture, provided that there shall be excluded from the
     operation of this paragraph this Indenture with respect to the Securities
     of any series other than that series and any indenture or indentures under
     which other securities, or certificates of interest or participation in
     other securities, of the Company are outstanding, if

             (i) this Indenture and such other indenture or indentures are
        wholly unsecured and such other indenture or indentures are either
        herein specifically described or hereafter qualified under the Trust
        Indenture Act, unless the Commission shall have found and declared by
        order pursuant to Section 305(b) or Section 307(c) of the Trust
        Indenture Act that differences exist between the provisions of this
        Indenture with respect to Securities of that series and one or more
        other series or the provisions of such other indenture or indentures
        which are so likely to involve a material conflict of interest as to
        make it necessary in the public interest or for the protection of
        investors to disqualify the Trustee from acting as such under this
        Indenture with respect to the Securities of that series and such other
        series or under such other indenture or indentures, or

             (ii) the Company shall have sustained the burden of proving, on
        application to the Commission and after opportunity for hearing thereon,
        that trusteeship under this Indenture with respect to the Securities of
        that series and such other series or such other indenture or indentures
        is not so likely to involve a material conflict of interest as to make
        it necessary in the public interest or for the protection of investors
        to disqualify the Trustee from acting as such under this Indenture with
        respect to the Securities of that series and such other series or under
        such other indenture or indentures;

          (2) the Trustee or any of its directors or executive officers is an
     obligor upon the Securities or an underwriter for the Company;

          (3) the Trustee directly or indirectly controls or is directly or
     indirectly controlled by or is under direct or indirect common control with
     the Company or an underwriter for the Company;

          (4) the Trustee or any of its directors or executive officers is a
     director, officer, partner, employee, appointee or representative of the
     Company, or of an underwriter (other than the Trustee itself) for the
     Company who is currently engaged in the business of underwriting, except
     that (i) one individual may be a director or an executive officer, or both,
     of the Trustee and a director or an executive officer, or both, of the
     Company but may not be at the same time an executive officer of both the
     Trustee and the Company; (ii) if and so long as the number of directors of
     the Trustee in office is more than nine, one additional individual may be a
     director or an executive officer, or both, of the Trustee and a director of
     the Company; and (iii) the Trustee may be designated by the Company or by
     any underwriter for the Company to act in the capacity of transfer agent,
     registrar, custodian, paying agent, fiscal agent, escrow agent or
     depositary, or in any other similar capacity, or, subject to the provisions
     of paragraph (1) of this Subsection, to act as trustee, whether under an
     indenture or otherwise;

          (5) 10% or more of the voting securities of the Trustee is
     beneficially owned either by the Company or by any director, partner or
     executive officer thereof, or 20% or more of such voting securities is
     beneficially owned, collectively, by any two or more of such persons; or
     10% or more of the voting securities of the Trustee is beneficially owned
     either by an underwriter for the Company or by any director, partner or
     executive officer thereof, or is beneficially owned, collectively, by any
     two or more such persons;

          (6) the Trustee is the beneficial owner of, or holds as collateral
     security for an obligation which is in default (as hereinafter in this
     Subsection defined), (i) 5% or more of the voting securities, or 10% or
     more of any other class of security, of the Company not including the
     Securities issued under this Indenture and securities issued under any
     other indenture under which the Trustee is also trustee, or (ii) 10% or
     more of any class of security of an underwriter for the Company;

                                       22
<PAGE>   28

          (7) the Trustee is the beneficial owner of, or holds as collateral
     security for an obligation which is in default (as hereinafter in this
     Subsection defined), 5% or more of the voting securities of any person who,
     to the knowledge of the Trustee, owns 10% or more of the voting securities
     of, or controls directly or indirectly or is under direct or indirect
     common control with, the Company;

          (8) the Trustee is the beneficial owner of, or holds as collateral
     security for an obligation which is in default (as hereinafter in this
     Subsection defined), 10% or more of any class of security of any person
     who, to the knowledge of the Trustee, owns 50% or more of the voting
     securities of the Company; or

          (9) the Trustee owns, on May 15 in any calendar year in the capacity
     of executor, administrator, testamentary or inter vivos trustee, guardian,
     committee or conservator, or in any other similar capacity, an aggregate of
     25% or more of the voting securities, or of any class of security, of any
     person, the beneficial ownership of a specified percentage of which would
     have constituted a conflicting interest under paragraph (6), (7) or (8) of
     this Subsection. As to any such securities of which the Trustee acquired
     ownership through becoming executor, administrator or testamentary trustee
     of an estate which included them, the provisions of the preceding sentence
     shall not apply, for a period of two years from the date of such
     acquisition, to the extent that such securities included in such estate do
     not exceed 25% of such voting securities or 25% of any such class of
     security. Promptly after May 15 in each calendar year, the Trustee shall
     make a check of its holdings of such securities in any of the
     above-mentioned capacities as of such May 15. If the Company fails to make
     payment in full of the principal of or interest on any of the Securities
     when and as the same becomes due and payable, and such failure continues
     for 30 days thereafter, the Trustee shall make a prompt check of its
     holdings of such securities in any of the above-mentioned capacities as of
     the date of the expiration of such 30-day period, and after such date,
     notwithstanding the foregoing provisions of this paragraph, all such
     securities so held by the Trustee, with sole or joint control over such
     securities vested in it, shall, but only so long as such failure shall
     continue, be considered as though beneficially owned by the Trustee for the
     purposes of paragraphs (6), (7) and (8) of this Subsection.

     The specification of percentages in paragraphs (5) to (9), inclusive, of
this Subsection shall not be construed as indicating that the ownership of such
percentages of the securities of a person is or is not necessary or sufficient
to constitute direct or indirect control for the purposes of paragraph (3) or
(7) of this Subsection.

     For the purposes of paragraphs (6), (7), (8) and (9) of this Subsection
only, (i) the terms "security" and "securities" shall include only such
securities as are generally known as corporate securities, but shall not include
any note or other evidence of indebtedness issued to evidence an obligation to
repay moneys lent to a person by one or more banks, trust companies or banking
firms, or any certificate of interest or participation in any such note or
evidence of indebtedness; (ii) an obligation shall be deemed to be "in default"
when a default in payment of principal shall have continued for 30 days or more
and shall not have been cured; and (iii) the Trustee shall not be deemed to be
the owner or holder of (A) any security which it holds as collateral security,
as trustee or otherwise, for an obligation which is not in default as defined
clause (ii) above, or (B) any security which it holds as collateral security
under this Indenture, irrespective of any default hereunder, or (C) any security
which it holds as agent for collection, or as custodian, escrow agent or
depositary, or in any similar representative capacity.

     (d) For the purposes of this Section:

          (1) The term "underwriter", when used with reference to the Company,
     means every person who, within three years prior to the time as of which
     the determination is made, has purchased from the Company with a view to,
     or has offered or sold for the Company in connection with, the distribution
     of any security of the Company outstanding at such time, or has
     participated or has had a direct or indirect participation in any such
     undertaking, or has participated or has had a participation in the direct
     or indirect underwriting of any such undertaking, but such term shall not
     include a person whose interest was limited to a commission from an
     underwriter or dealer not in excess of the usual and customary
     distributors' or sellers' commission.

                                       23
<PAGE>   29

          (2) The term "director" means any director of a corporation or any
     individual performing similar functions with respect to any organization,
     whether incorporated or unincorporated.

          (3) The term "person" means an individual, a corporation, a
     partnership, an association, a joint-stock company, a trust, an
     unincorporated organization or a government or political subdivision
     thereof. As used in this paragraph, the term "trust" shall include only a
     trust where the interest or interests of the beneficiary or beneficiaries
     are evidenced by a security.

          (4) The term "voting security" means any security presently entitling
     the owner or holder thereof to vote in the direction or management of the
     affairs of a person, or any security issued under or pursuant to any trust,
     agreement or arrangement whereby a trustee or trustees or agent or agents
     for the owner or holder of such security are presently entitled to vote in
     the direction or management of the affairs of a person.

          (5) The term "Company" means any obligor upon the Securities.

          (6) The term "executive officer" means the president, every vice
     president, every trust officer, the secretary and the treasurer of a
     corporation, and any individual customarily performing similar functions
     with respect to any organization whether incorporated or unincorporated,
     but shall not include the chairman of the board of directors.

     (e) The percentages of voting securities and other securities specified in
this Section shall be calculated in accordance with the following provisions:

          (1) A specified percentage of the voting securities of the Trustee,
     the Company or any other person referred to in this Section (each of whom
     is referred to as a "person" in this paragraph) means such amount of the
     outstanding voting securities of such person as entitles the holder or
     holders thereof to cast such specified percentage of the aggregate votes
     which the holders of all the outstanding voting securities of such person
     are entitled to cast in the direction or management of the affairs of such
     person.

          (2) A specified percentage of a class of securities of a person means
     such percentage of the aggregate amount of securities of the class
     outstanding.

          (3) The term "amount," when used in regard to securities, means the
     principal amount if relating to evidences of indebtedness, the number of
     shares if relating to capital shares and the number of units if relating to
     any other kind of security.

          (4) The term "outstanding" means issued and not held by or for the
     account of the issuer. The following securities shall not be deemed
     outstanding within the meaning of this definition:

             (i) securities of an issuer held in a sinking fund relating to
        securities of the issuer of the same class;

             (ii) securities of an issuer held in a sinking fund relating to
        another class of securities of the issuer, if the obligation evidenced
        by such other class of securities is not in default as to principal or
        interest or otherwise;

             (iii) securities pledged by the issuer thereof as security for an
        obligation of the issuer not in default as to principal or interest or
        otherwise; and

             (iv) securities held in escrow if placed in escrow by the issuer
        thereof;

          provided, however, that any voting securities of an issuer shall be
     deemed outstanding if any person other than the issuer is entitled to
     exercise the voting rights thereof.

          (5) A security shall be deemed to be of the same class as another
     security if both securities confer upon the holder or holders thereof
     substantially the same rights and privileges; provided, however, that, in
     the case of secured evidences of indebtedness, all of which are issued
     under a single indenture, differences in the interest rates or maturity
     dates of various series thereof shall not be deemed sufficient to
     constitute such series different classes; and provided, further, that, in
     the case of unsecured evidences of

                                       24
<PAGE>   30

     indebtedness, differences in the interest rates or maturity dates thereof
     shall not be deemed sufficient to constitute them securities of different
     classes, whether or not they are issued under a single indenture.

     Section 6.8. Corporate Trustee Required; Eligibility.

     There shall at all times be a Trustee hereunder which shall be a
corporation organized and doing business under the laws of the United States of
America, any State thereof or the District of Columbia, authorized under such
laws to exercise corporate trust powers, having a combined capital and surplus
of at least $1,000,000 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, the combined capital
and surplus of such corporation shall be deemed to be its combined capital and
surplus as set forth in its most recent report of condition so published. If at
any time the Trustee shall cease to be eligible in accordance with the
provisions of this Section, it shall resign immediately in the manner and with
the effect hereinafter specified in this Article.

     Section 6.9. 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 shall become effective until the
acceptance of appointment by the successor Trustee in accordance with the
applicable requirements of Section 6.10.

     (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 the
instrument of acceptance by a successor Trustee required by Section 6.10 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 with respect to the
Securities of such series.

     (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:

          (1) the Trustee shall fail to comply with Section 6.7(a) after written
     request therefor by the Company or by any Holder who has been a bona fide
     Holder of a Security for at least six months, or

          (2) the Trustee shall cease to be eligible under Section 6.8 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 affairs 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 all Securities, or (ii) subject to Section 5.12, 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 with respect to all
Securities and the appointment of a successor Trustee or Trustees.

     (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) and shall comply with the applicable
requirements of Section 6.10. 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 Securities of such
series delivered to the Company and the
                                       25
<PAGE>   31

retiring Trustee, the successor Trustee so appointed shall, forthwith upon its
acceptance of such appointment in accordance with the applicable requirements of
Section 6.10, 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 with respect to the Securities of any series
shall have been so appointed by the Company or the Holders and accepted
appointment in the manner required by Section 6.10, any Holder who has been a
bona fide Holder of a Security of such series 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 with respect
to the Securities of such series.

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

     Section 6.10. 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 the 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.

     (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 (1) 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, (2)
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 of 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
(3) 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 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, as the case may be.

                                       26
<PAGE>   32

     (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.

     Section 6.11. 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,
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 6.12. Preferential Collection of Claims Against Company.

     (a) Subject to Subsection (b) of this Section, if the Trustee shall be or
shall become a creditor, directly or indirectly, secured or unsecured, of the
Company within four months prior to a default, as defined in Subsection (c) of
this Section, or subsequent to such a default, then, unless and until such
default shall be cured, the Trustee shall set apart and hold in a special
account for the benefit of the Trustee individually, the Holders of the
Securities and the holders of other indenture securities, as defined in
Subsection (c) of this Section:

          (1) an amount equal to any and all reductions in the amount due and
     owing upon any claim as such creditor in respect of principal or interest,
     effected after the beginning of such four months' period and valid as
     against the Company and its other creditors, except any such reduction
     resulting from the receipt or disposition of any property described in
     paragraph (2) of this Subsection, or from the exercise of any right of
     set-off which the Trustee could have exercised if a petition in bankruptcy
     had been filed by or against the Company upon the date of such default; and

          (2) all property received by the Trustee in respect of any claims as
     such creditor, either as security therefor, or in satisfaction or
     composition thereof, or otherwise, after the beginning of such four months'
     period, or an amount equal to the proceeds of any such property, if
     disposed of, subject, however, to the rights, if any, of the Company and
     its other creditors in such property or such proceeds.

          Nothing herein contained, however, shall affect the right of the
     Trustee:

             (A) to retain for its own account (i) payments made on account of
        any such claim by any Person (other than the Company) who is liable
        thereon, (ii) the proceeds of the bona fide sale of any such claim by
        the Trustee to a third Person, and (iii) distributions made in cash,
        securities or other property in respect of claims filed against the
        Company in bankruptcy or receivership or in proceedings for
        reorganization pursuant to the Federal Bankruptcy Act or applicable
        State law;

             (B) to realize, for its own account, upon any property held by it
        as security for any such claim, if such property was so held prior to
        the beginning of such four months' period;

             (C) to realize, for its own account, but only to the extent of the
        claim hereinafter mentioned, upon any property held by it as security
        for any such claim, if such claim was created after the beginning of
        such four months' period and such property was received as security
        therefor simultaneously with the creation thereof, and if the Trustee
        shall sustain the burden of proving that at the time such property was
        so received the Trustee had no reasonable cause to believe that a
        default, as defined in Subsection (c) of this Section, would occur
        within four months; or

             (D) to receive payment on any claim referred to in paragraph (B) or
        (C), against the release of any property held as security for such claim
        as provided in paragraph (B) or (C), as the case may be, to the extent
        of the fair value of such property.

                                       27
<PAGE>   33

     For the purposes of paragraphs (B), (C) and (D), property substituted after
the beginning of such four months' period for property held as security at the
time of such substitution shall, to the extent of the fair value of the property
released, have the same status as the property released, and, to the extent that
any claim referred to in any of such paragraphs is created in renewal of or in
substitution for or for the purpose of repaying or refunding any pre-existing
claim of the Trustee as such creditor, such claim shall have the same status as
such pre-existing claim.

     If the Trustee shall be required to account, the funds and property held in
such special account and the proceeds thereof shall be apportioned among the
Trustee, the Holders and the holders of other indenture securities in such
manner that the Trustee, the Holders and the holders of other indenture
securities realize, as a result of payments from such special account and
payments of dividends on claims filed against the Company in bankruptcy or
receivership or in proceedings for reorganization pursuant to the Federal
Bankruptcy Act or applicable State law, the same percentage of their respective
claims, figured before crediting to the claim of the Trustee anything on account
of the receipt by it from the Company of the funds and property in such special
account and before crediting to the respective claims of the Trustee and the
Holders and the holders of other indenture securities dividends on claims filed
against the Company in bankruptcy or receivership or in proceedings for
reorganization pursuant to the Federal Bankruptcy Act or applicable State law,
but after crediting thereon receipts on account of the indebtedness represented
by their respective claims from all sources other than from such dividends and
from the funds and property so held in such special account. As used in this
paragraph, with respect to any claim, the term "dividends" shall include any
distribution with respect to such claim, in bankruptcy or receivership or
proceedings for reorganization pursuant to the Federal Bankruptcy Act or
applicable State law, whether such distribution is made in cash, securities or
other property, but shall not include any such distribution with respect to the
secured portion, if any, of such claim. The court in which such bankruptcy,
receivership or proceedings for reorganization is pending shall have
jurisdiction (i) to apportion among the Trustee, the Holders and the holders of
other indenture securities, in accordance with the provisions of this paragraph,
the funds and property held in such special account and proceeds thereof, or
(ii) in lieu of such apportionment, in whole or in part, to give to the
provisions of this paragraph due consideration in determining the fairness of
the distributions to be made to the Trustee and the Holders and the holders of
other indenture securities with respect to their respective claims, in which
event it shall not be necessary to liquidate or to appraise the value of any
securities or other property held in such special account or as security for any
such claim, or to make a specific allocation of such distributions as between
the secured and unsecured portions of such claims, or otherwise to apply the
provisions of this paragraph as a mathematical formula.

     Any Trustee which has resigned or been removed after the beginning of such
four months' period shall be subject to the provisions of this Subsection as
though such resignation or removal had not occurred. If any Trustee has resigned
or been removed prior to the beginning of such four months' period, it shall be
subject to the provisions of this Subsection if and only if the following
conditions exist:

          (i) the receipt of property or reduction of claim which would have
     given rise to the obligation to account, if such Trustee had continued as
     Trustee, occurred after the beginning of such four months' period; and

          (ii) such receipt of property or reduction of claim occurred within
     four months after such resignation or removal.

     (b) There shall be excluded from the operation of Subsection (a) of this
Section a creditor relationship arising from:

          (1) the ownership or acquisition of securities issued under any
     indenture, or any security or securities having a maturity of one year or
     more at the time of acquisition by the Trustee;

          (2) advances authorized by a receivership or bankruptcy court of
     competent jurisdiction or by this Indenture, for the purpose of preserving
     any property which shall at any time be subject to the lien of this
     Indenture or of discharging tax liens or other prior liens or encumbrances
     thereon, if notice of such

                                       28
<PAGE>   34

     advances and of the circumstances surrounding the making thereof is given
     to the Holders at the time and in the manner provided in this Indenture;

          (3) disbursements made in the ordinary course of business in the
     capacity of trustee under an indenture, transfer agent, registrar,
     custodian, paying agent, fiscal agent or depositary, or other similar
     capacity;

          (4) an indebtedness created as a result of services rendered or
     premises rented; or an indebtedness created as a result of goods or
     securities sold in a cash transaction, as defined in Subsection (c) of this
     Section;

          (5) the ownership of stock or of other securities of a corporation
     organized under the provisions of Section 25(a) of the Federal Reserve Act,
     as amended, which is directly or indirectly a creditor of the Company; and

          (6) the acquisition, ownership, acceptance or negotiation of any
     drafts, bills of exchange, acceptances or obligations which fall within the
     classification of self-liquidating paper, as defined in Subsection (c) of
     this Section.

     (c) For the purposes of this Section only:

          (1) the term "default" means any failure to make payment in full of
     the principal of or interest on any of the Securities or upon the other
     indenture securities when and as such principal or interest becomes due and
     payable;

          (2) the term "other indenture securities" means securities upon which
     the Company is an obligor outstanding under any other indenture (i) under
     which the Trustee is also trustee, (ii) which contains provisions
     substantially similar to the provisions of this Section, and (iii) under
     which a default exists at the time of the apportionment of the funds and
     property held in such special account;

          (3) the term "cash transaction" means any transaction in which full
     payment for goods or securities sold is made within seven days after
     delivery of the goods or securities in currency or in checks or other
     orders drawn upon banks or bankers and payable upon demand;

          (4) the term "self-liquidating paper" means any draft, bill of
     exchange, acceptance or obligation which is made, drawn, negotiated or
     incurred by the Company for the purpose of financing the purchase,
     processing, manufacturing, shipment, storage or sale of goods, wares or
     merchandise and which is secured by documents evidencing title to,
     possession of, or a lien upon, the goods, wares or merchandise or the
     receivables or proceeds arising from the sale of the goods, wares or
     merchandise previously constituting the security, provided the security is
     received by the Trustee simultaneously with the creation of the creditor
     relationship with the Company arising from the making, drawing, negotiating
     or incurring of the draft, bill of exchange, acceptance or obligation;

          (5) the term "Company" means any obligor upon the Securities; and

          (6) the term "Federal Bankruptcy Act" means the Bankruptcy Act or
     Title 11 of the United States Code.

                                  ARTICLE VII.

               HOLDERS' LISTS AND REPORTS BY TRUSTEE AND COMPANY

     Section 7.1. Company to Furnish Trustee Names and Addresses of Holders.

          The Company will furnish or cause to be furnished to Trustee

          (a) semi-annually, not later than 15 days after the Regular Record
     Date and not later than 15 days after the date which is six months after
     the Regular Record Date, for each series of Securities, a list, in such
     form as the Trustee may reasonably require, of the names and addresses of
     the Holders of the Securities of such series as of such Regular Record
     Date, and
                                       29
<PAGE>   35

          (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.

     Section 7.2. Preservation of Information; Communications to Holders.

     (a) The Trustee shall preserve, in as current a form as is reasonably
practicable, the names and addresses of Holders contained in the most recent
list furnished to the Trustee as provided in Section 7.1. The Trustee may
destroy any list furnished to it as provided in Section 7.1 upon receipt of a
new list so furnished.

     (b) If three or more Holders (herein referred to as "applicants") apply in
writing to the Trustee, and furnish to the Trustee reasonable proof that each
such applicant has owned a Security for a period of at least six months
preceding the date of such application, and such application states that the
applicants desire to communicate with other Holders with respect to their rights
under this Indenture or under the Securities and is accompanied by a copy of the
form of proxy or other communication which such applicants propose to transmit,
then the Trustee shall, within five business days after the receipt of such
application, at its election, either

          (i) afford such applicants access to the information preserved at the
     time by the Trustee in accordance with Section 7.2(a), or

          (ii) inform such applicants as to the approximate number of Holders
     whose names and addresses appear in the information preserved at the time
     by the Trustee in accordance with Section 7.2(a), and as to the approximate
     cost of mailing to such Holders the form of proxy or other communication,
     if any, specified in such application.

     If the Trustee shall elect not to afford such applicants access to such
information, the Trustee shall, upon the written request of such applicants,
mail to each Holder whose name and address appear in the information preserved
at the time by the Trustee in accordance with Section 7.2(a) a copy of the form
of proxy or other communication which is specified in such request, with
reasonable promptness after a tender to the Trustee of the material to be mailed
and of payment, or provision for the payment, of the reasonable expenses of
mailing, unless within five days after such tender the Trustee shall mail to
such applicants and file with the Commission, together with a copy of the
material to be mailed, a written statement to the effect that, in the opinion of
the Trustee, such mailing would be contrary to the best interest of the Holders
or would be in violation of applicable law. Such written statement shall specify
the basis of such opinion. If the Commission, after opportunity for a hearing
upon the objections specified filed, shall enter an order refusing to sustain
any of such objections or if, after the entry of an order sustaining one or more
of such objections, the Commission shall find, after notice and opportunity for
hearing, that all the objections so sustained have been met and shall enter an
order so declaring, the Trustee shall mail copies of such material to all such
Holders with reasonable promptness after the entry of such order and the renewal
of such tender; otherwise the Trustee shall be relieved of any obligation or
duty to such applicants respecting their application.

     (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 Section 7.2(b), 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 Section 7.2(b).

     Section 7.3. Reports by Trustee.

     (a) Within 60 days after May 15 of each year commencing with the year 2001,
the Trustee shall transmit by mail to all Holders, as their names and addresses
appear in the Security Register, a brief report dated as of such May 15 with
respect to:

          (1) its eligibility under Section 6.8 and its qualifications under
     Section 6.7, or in lieu thereof, if to the best of its knowledge it has
     continued to be eligible and qualified under said Sections, a written
     statement to such effect;
                                       30
<PAGE>   36

          (2) the character and amount and the circumstances surrounding the
     making of any advances by the Trustee (as such) which remain unpaid on the
     date of such report, and for the reimbursement of which it claims or may
     claim a lien or charge, prior to that of the Securities, on any property or
     funds held or collected by it as Trustee, except that the Trustee shall not
     be required (but may elect) to report such advances if such advances so
     remaining unpaid aggregate not more than 1/2 of 1% of the principal amount
     of the Securities Outstanding on the date of such report:

          (3) the amount, interest rate and maturity date of all other
     indebtedness owing by the Company (or by any other obligor on the
     Securities) to the Trustee in its individual capacity on the date of such
     report, with a brief description of any property held as collateral
     security therefor, except an indebtedness based upon a creditor
     relationship arising in any manner described in Section 6.12(b)(2), (3),
     (4) or (6);

          (4) the property and funds, if any, physically in the possession of
     the Trustee, as Trustee, on the date of such report;

          (5) any additional issue of Securities which the Trustee has not
     previously reported; and

          (6) any action taken by the Trustee in the performance of its duties
     hereunder which it has not previously reported and which in its opinion
     materially affects the Securities, except action in respect of a default,
     notice of which has been or is to be withheld by the Trustee in accordance
     with Section 6.2.

     (b) The Trustee shall transmit by mail to all Holders, as their names and
addresses appear in the Security Register, a brief report with respect to the
character and amount of any advances (and if the Trustee elects so to state, the
circumstances surrounding the making thereof) made by the Trustee (as such)
since the date of the last report transmitted, pursuant to Subsection (a) of
this Section (or if no report has yet been so transmitted, since the date of
execution of this instrument) for the reimbursement of which it claims or may
claim a lien or charge, prior to that of the Securities, on property or funds
held or collected by it as Trustee and which it has not previously reported
pursuant to this Subsection, except that the Trustee shall not be required (but
may elect) to report such advances if such advances remaining unpaid at any time
aggregate 10% or less of the principal amount of the Securities Outstanding at
such time, such report to be transmitted within 90 days after such time.

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

     Section 7.4. Reports by Company.

     The Company shall:

          (1) 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 may be required to file
     with the Commission pursuant to Section 13 or Section 15(d) of the
     Securities Exchange Act of 1934; or, if the Company is not required to file
     information, documents or reports pursuant to either of said Sections, then
     it shall file with the Trustee and the Commission, in accordance with rules
     and regulations prescribed from time to time 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 in
     respect of a security listed and registered on a national securities
     exchange as may be prescribed from time to time in such rules and
     regulations;

          (2) file with the Trustee and the Commission, in accordance with rules
     and regulations prescribed from to time by the Commission, such additional
     information, documents and reports with respect to compliance by the
     Company with the conditions and covenants of this Indenture as may be
     required from time to time by such rules and regulations; and

                                       31
<PAGE>   37

          (3) transmit by mail to all Holders, as their names and addresses
     appear in the Security Register, within 30 days after the filing thereof
     with the Trustee, such summaries of any information, documents and reports
     required to be filed by the Company pursuant to paragraphs (1) and (2) of
     this Section as may be required by rules and regulations prescribed from
     time to time by the Commission.

                                 ARTICLE VIII.

                            SUPPLEMENTAL INDENTURES

     Section 8.1. 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 Person to the Company and
     the assumption by any such successor of the covenants of the Company herein
     and in the Securities;

          (2) to add to the covenants of the Company for the benefit of the
     Holders of all or any series of Securities (and if such covenants are to be
     for the benefit of less than all series of Securities, stating that such
     covenants are expressly being included solely for the benefit of such
     series) or to surrender any right or power herein conferred upon the
     Company;

          (3) to add any additional Events of Default;

          (4) to add to or change any of the provisions of this Indenture to
     such extent as shall be necessary to permit or facilitate the issuance of
     Securities in bearer form, registrable or not registrable as to principal,
     and with or without interest coupons;

          (5) to change or eliminate any of the provisions of this Indenture,
     provided that any such change or elimination shall become effective only
     when there is no Security Outstanding of any series created prior to the
     execution of such supplemental indenture which is entitled to the benefit
     of such provision;

          (6) to secure the Securities;

          (7) to establish the form or terms of Securities of any series as
     permitted by Sections 2.1 and 3.1;

          (8) 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 6.10(b);

          (9) to revise the fee schedule attached as Exhibit B;

          (10) to make provision with respect to the conversion rights of
     Holders pursuant to the requirements of Article XI; or

          (11) 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 of Securities of any series in any material
     respect.

     Section 8.2. Supplemental Indentures with Consent of Holders.

     With the consent of the Holders of not less than 66 2/3% in principal
amount of the Outstanding Securities of each series affected by such
supplemental indenture, 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

                                       32
<PAGE>   38

Holders of Securities of such series under this Indenture; provided, however,
that no such supplemental indenture shall, without a consent of the Holder of
each Outstanding Security affected thereby,

          (1) change the Stated Maturity of the principal of, or any installment
     of principal of or interest on, any Security, or reduce the principal
     amount thereof or the redemption thereof, or change any 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, in the case of redemption, on or after the Redemption Date), or
     adversely affect the right to convert any Security pursuant to Article XI
     (except to the extent permitted by Section 8.1), or

          (2) reduce the percentage in principal amount of the Outstanding
     Securities of any series, 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 or Section 5.11,
     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,
     provided, however, that this clause shall not be deemed to require the
     consent of any Holder with respect to changes in the references to "the
     Trustee" and concomitant changes in this Section, or the deletion of this
     proviso, in accordance with the requirements of Sections 6.10(b) and
     8.1(8).

     A supplemental indenture which 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 which modifies the
rights of the Holders of Securities of such series with 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 to
approve the particular form of any proposed supplemental indenture, but it shall
be sufficient if such Act shall approve the substance thereof.

     Section 8.3. Execution of Supplemental Indentures.

     In executing, or accepting the additional trusts created by, any
supplemental indenture permitted by this Article or the modifications thereby of
the trusts created by this Indenture, the Trustee shall be entitled to receive,
and (subject to Section 6.1) 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 8.4. Effect of Supplemental Indentures.

     Upon the execution of any supplemental indenture under this Article, 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 8.5. Conformity with Trust Indenture Act.

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

     Section 8.6. Reference in Securities to Supplemental Indentures.

     Securities of any series authenticated and delivered after the execution of
any supplemental indenture pursuant to this Article 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 of any series so modified as to conform, in the opinion of the
Trustee and the Company, to any such supplemental indenture may be prepared and
executed by the Company and authenticated by the Trustee and delivered by the
Company in exchange for Outstanding Securities of such series.

                                       33
<PAGE>   39

     New Securities of any series issued and exchanged pursuant to this Section
shall be entitled to all the benefits of this Indenture as the same is amended,
modified or supplemented by any such supplemental indenture.

                                  ARTICLE IX.

                                   COVENANTS

     Section 9.1. Payment of Principal and Interest.

     The Company covenants and agrees for the benefit of each series of
Securities that it will duly and punctually pay the principal of and interest on
the Securities of that series in accordance with the terms of the Securities of
such series and this Indenture. The Company further covenants that it will not
pay any dividends on any class of stock of the Company until all accrued and
unpaid interest on the Securities has been paid.

     Section 9.2. Money for Securities Payments to Be Held 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 interest 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 interest 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 for any series of
Securities, it will, prior to each due date of the principal of or interest on
any Securities of that series, 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.

     The Company will cause each Paying Agent for any series of Securities 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, that such Paying Agent will:

          (1) hold all sums held by it for the payment of the principal of or
     interest on Securities of that series 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;

          (2) give the Trustee written 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 or interest on the Securities of that series; and

          (3) 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.

     The Company may at any time, for the purpose of obtaining the satisfaction
and discharge of this Indenture or for any other purpose, pay, or by Company
Order direct any Paying Agent to pay, to the Trustee all sums held in trust by
the Company or such Paying Agent, such sums to be held by the Trustee upon the
same trusts as those upon which such sums were held by the Company or such
Paying Agent; and, upon such payment by any Paying Agent to the Trustee, such
Paying Agent shall be released from all further liability with respect to such
money.

     Any money deposited with the Trustee or any Paying Agent or then held by
the Company, in trust for the payment of the principal of or interest on any
Security of any series and remaining unclaimed for two years after such
principal or interest has become due and payable shall be paid to the Company on
Company Request, or (if then held by the Company) shall be discharged from such
trust; and the Holder of such Security shall thereafter, as an unsecured general
creditor, look only to the Company for payment thereof, and all liability of the
Trustee or such Paying Agent with respect to such trust money, and all liability
of the Company as trustee thereof, shall thereupon cease.

                                       34
<PAGE>   40

     Section 9.3. Notice of a Change of Control.

     If there is a Change of Control, the Company shall transmit by mail to all
Holders of each series of Securities then Outstanding, as their names and
addresses appear in the Security Register, written notice of the occurrence of
such Change of Control within ten (10) days following such occurrence.

                                   ARTICLE X.

                            REDEMPTION OF SECURITIES

     Section 10.1. Applicability of Article.

     Securities of any series which are redeemable before their Stated Maturity
shall be redeemable in accordance with their terms and this Article.

     Section 10.2. Election to Redeem.

     The election of the Company to redeem any Securities shall be evidenced by
a Board Resolution. The Company may not redeem any Securities during any
Conversion Period.

     Section 10.3. Notice of Redemption.

     Notice of redemption shall be given by first-class mail, postage prepaid,
mailed not less than 45 days prior to the Redemption Date, to each Holder of
Securities to be redeemed, at his address appearing in the Security Register.

     All notices of redemption shall state:

          (1) the Redemption Date,

          (2) the Redemption Price,

          (3) 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, and

          (4) the place or places where such Securities are to be surrendered
     for payment of the Redemption Price.

     Notice of redemption of Securities shall be given by the Company or, at the
Company's request, by the Trustee in the name and at the expense of the Company.

     Section 10.4. Deposit of Redemption Price.

     Prior to 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 9.2) 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 10.5. Securities Payable on Redemption Date.

     Notice of Redemption having been given as aforesaid, the Securities so to
be redeemed, which have not been converted as provided in Section 11.1, shall,
on the Redemption Date, become due and payable at the Redemption Price therein
specified, and from and after such date (unless the Company shall default in the
payment of the Redemption Price and accrued interest) 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.

     If any Security called for redemption shall not be paid upon surrender
thereof for redemption, the principal shall continue to bear interest until
paid.

                                       35
<PAGE>   41

                                  ARTICLE XI.

                            CONVERSION OF SECURITIES

     Section 11.1. Right of Conversion.

     The Holder of any Security or Securities of any series shall have the
right, at the Holder's option, at any time during (i) the Regular Conversion
Period applicable to such series (except that with respect to any Security or
Securities which shall be called for redemption, such right shall terminate at
the close of business on the Redemption Date for such Security or Securities,
unless the Company shall default in payment due upon redemption thereof), and
(ii) any Special Conversion Period applicable to such series and such Holder to
convert, subject to the terms and provisions of this Article XI, the principal
of any such Security or Securities into fully paid and non-assessable shares of
Common Stock of the Company, at the rate of shares of Common Stock for each
$1,000 principal amount of Securities to be determined for each series as
contemplated by Section 3.1 (the "Conversion Rate") or, in case an adjustment
therein has taken place pursuant to the provisions of Section 11.4, then at the
rate as so adjusted; provided, however, that no Holder may convert less than all
of the principal amount of any Security surrendered for conversion, and,
provided further, that no Holder may convert any Security of a series unless all
Securities of such series held by such Holder are surrendered for conversion.
The conversion right shall be exercised by the surrender of the Security or
Securities, the principal of which is so to be converted, to the Company at any
time during usual business hours at its principal office in Omaha, Nebraska,
accompanied by written notice, substantially in the form set forth in Section
2.4, executed by the Holder of such Security or Securities, that the Holder
elects to convert such Security or Securities. All Securities surrendered to the
Company for conversion shall be cancelled by it, and no Securities shall be
issued in lieu thereof.

     Section 11.2. Issuance of Common Stock; Time of Conversion.

     Within sixty (60) days following the surrender, as herein provided, of any
Security or Securities for conversion, the Company shall issue a certificate or
certificates representing the number of fully paid and non-assessable shares of
Common Stock of the Company into which such Security or Securities may be
converted. Subject to the following provisions of this paragraph and of Section
12.4, such conversion shall be deemed to have been made immediately prior to the
close of business on the date that such Security or Securities shall have been
surrendered in satisfactory form for conversion, so that the rights of the
Holder as a Holder shall cease with respect to such Security or Securities at
such time, and the Person or Persons entitled to receive the shares of Common
Stock deliverable upon conversion of such Security or Securities shall be
treated for all purposes as having become the record holder or holders of such
shares of Common Stock at such time; provided, however, that no such surrender
on any date when the stock transfer books of the Company shall be closed shall
be effective to constitute the Person or Persons entitled to receive the shares
of Common Stock deliverable upon such conversion as the record holder or holders
of such shares of Common Stock on such date, but such surrender shall be
effective to constitute the Person or Persons entitled to receive such shares of
Common Stock as the record holder or holders thereof for all purposes
immediately prior to the close of business on the next succeeding day on which
such stock transfer books are open. The date on which a Security shall have been
deemed to have been converted is referred to herein as the "Conversion Date".

     Section 11.3. Adjustments in Respect of Interest.

     Any Security of any series converted during the Conversion Period
applicable to such series shall cease to accrue interest on the principal amount
thereof as of the applicable Conversion Interest Termination Date.

     Section 11.4. Adjustment of Conversion Rate.

     The Conversion Rate applicable to any series of Securities shall be subject
to adjustment as follows:

          (a) In case the Company shall (i) pay a dividend, or make a
     distribution, in shares of Common Stock, on the Common Stock, (ii)
     subdivide the Outstanding Common Stock into a greater number of shares,
     (iii) combine the Outstanding Common Stock into a smaller number of shares,
     or (iv) reclassify the Common Stock, the Conversion Rate in effect
     immediately prior thereto shall be adjusted so that the Holder of any
     Security thereafter surrendered for conversion shall be entitled to receive
     the number of
                                       36
<PAGE>   42

     shares of Common Stock which such Holder would have owned or have been
     entitled to receive after the happening of any of the events described
     above had such Security been converted immediately prior to the happening
     of such event. If any dividend or distribution of the type described in
     clause (i) above is not so paid or made, the Conversion Rate shall again be
     adjusted to the Conversion Rate which would then be in effect if such
     dividend or distribution had not been declared. An adjustment made pursuant
     to this Section 11.4(a) shall become effective immediately after the record
     date in the case of a dividend and shall become effective immediately after
     the effective date in the case of subdivision, combination or
     reclassification.

          (b) In case the Company shall issue rights, options or warrants to all
     holders of any class or series of its Common Stock entitling them (for a
     period expiring within 45 days after the date fixed for determination of
     stockholders entitled to receive such rights, options or warrants) to
     subscribe for or purchase Common Stock at a price per share less than the
     Average Closing Market Price at the record date for the determination of
     stockholders entitled to receive such rights, options or warrants, the
     Conversion Rate in effect immediately prior thereto shall be adjusted so
     that the same shall equal the Conversion Rate determined by multiplying the
     Conversion Rate in effect immediately prior to the date of the issuance of
     such rights, options or warrants by a fraction of which the numerator shall
     be the number of shares of Common Stock outstanding on the date of issuance
     of such rights, options or warrants plus the number of additional shares of
     Common Stock offered for subscription or purchase, and of which the
     denominator shall be the number of shares of Common Stock outstanding on
     the date of issuance of such rights, options or warrants plus the number of
     shares which the aggregate offering price of the total number of shares so
     offered would purchase at such Average Closing Market Price. Such
     adjustment shall be made successively whenever any such rights or warrants
     are issued, and shall become effective immediately after the opening of
     business on the day following the record date for the determination of the
     stockholders entitled to receive such rights or warrants. To the extent
     that shares of Common Stock are not delivered after the expiration of such
     rights, options or warrants, the Conversion Rate shall be readjusted to the
     Conversion Rate which would then be in effect had the adjustments made upon
     the issuance of such rights or warrants been made on the basis of delivery
     of only the number of shares of Common Stock actually delivered. If such
     rights, options or warrants are not so issued, the Conversion Rate shall
     again be adjusted to be the Conversion Rate which would then be in effect
     if such record date for the determination of stockholders entitled to
     receive such rights or warrants had not been fixed. In determining whether
     any rights, options or warrants entitle the holders to subscribe for or
     purchase shares of Common Stock at less than such Average Closing Market
     Price, and in determining the aggregate offering price of such shares of
     Common Stock, there shall be taken into account any consideration received
     by the Company for such rights, options or warrants, the value of such
     consideration, if other than cash, to be determined by the Board of
     Directors.

          (c) In case the Company shall, by dividend or otherwise, distribute to
     all holders of any class or series of Common Stock (excluding any
     distribution in connection with the liquidation, dissolution or winding up
     of the Company, whether voluntary or involuntary) any shares of any class
     of capital stock of the Company (other than Common Stock) or evidences of
     its indebtedness or assets (other than Cash) or rights, options or warrants
     to subscribe for or purchase any of its Securities (excluding those
     referred to in Section 11.4(b) hereof) (any of the foregoing hereinafter in
     this Section 11.4(c) called the "Distributed Securities"), then, the
     Conversion Rate shall be adjusted so that the same shall equal the
     Conversion Rate determined by multiplying the Conversion Rate in effect
     immediately prior to the date of such distribution by a fraction of which
     the numerator shall be the Average Closing Market Price on the record date
     described below, and the denominator shall be the Average Closing Market
     Price on such record date less the fair market value on such record date
     (as determined by the Board of Directors of the Company, whose
     determination shall be conclusive, and described in a certificate filed
     with the Trustee) of the Distributed Securities so distributed applicable
     to one share of Common Stock. Such adjustment shall become effective
     immediately after the record date for the determination of stockholders
     entitled to receive such distribution. Notwithstanding the foregoing, in
     the event the then fair market value (as so determined) of the portion of
     the Distributed Securities so distributed applicable to one share of Common
     Stock is equal to or greater than the Average Closing Market Price on the
     record date, in lieu of
                                       37
<PAGE>   43

     the foregoing adjustment, adequate provision shall be made so that each
     Holder shall have the right to receive, upon conversion of such Holder's
     Securities, the amount of Distributed Securities such Holder would have
     received had such Holder converted such Securities on such record date. In
     the event that such distribution is not so paid or made, the Conversion
     Rate shall again be adjusted to the Conversion Rate which would then be in
     effect if such distribution had not been declared. If the Board of
     Directors determines the fair market value of any distribution for purposes
     of this Section 11.4(c) by reference to the actual or when issued trading
     market for any securities, it must in doing so consider the prices in such
     market over the same period used in computing such Average Closing Market
     Price.

          Notwithstanding the foregoing provisions of this Section 11.4(c), no
     adjustment shall be made thereunder for any distribution of Distributed
     Securities if the Company makes proper provision so that each Holder of a
     Security who converts such Security (or any portion thereof) after such
     record date for such distribution shall be entitled to receive upon such
     conversion, in addition to the shares of Common Stock issuable upon such
     conversion, the amount and kind of Distributed Securities that such Holder
     would have been entitled to receive if such Holder had, immediately prior
     to such record date, converted such Security for Common Stock; provided
     that, with respect to any Distributed Securities that are convertible,
     exchangeable or exercisable, the foregoing provision shall only apply to
     the extent (and so long as) the Distributed Securities receivable upon
     conversion of such Security would be convertible, exchangeable or
     exercisable, as applicable, without any loss of rights or privileges for a
     period of at least 60 days following conversion of such Security.

          In the event the Company implements a stockholder rights plan, such
     rights plan shall provide that upon conversion of the Securities the
     Holders shall receive, in addition to the Common Stock issuable upon such
     conversion, the rights issued under such rights plan (notwithstanding the
     occurrence of an event causing such rights to separate from the Common
     Stock at or prior to the time of conversion).

          (d) In case the Company shall, by dividend or otherwise, distribute to
     all holders of any class of Common Stock cash (excluding any cash that is
     distributed upon a merger or consolidation or as part of a distribution
     referred to in Section 11.4(c)) in an aggregate amount that, combined
     together with (i) the aggregate amount of any other such distributions to
     all holders of any class of Common Stock made exclusively in cash within
     the 12 months preceding the date of payment of such distribution, and in
     respect of which no adjustment pursuant to this Section 11.4(d) has been
     made, and (ii) the aggregate of any cash plus the fair market value (as
     determined by the Board of Directors, whose determination shall be
     conclusive and described in a resolution of the Board of Directors) of
     consideration payable in respect of any tender offer by the Company for all
     or any portion of any class of its Common Stock concluded within the 12
     months preceding the date of payment of such distribution, and in respect
     of which no adjustment pursuant to Section 11.4(e) has been made, exceeds
     10% of the product of the Average Closing Market Price on the record date
     with respect to such distribution and the number of shares of Common Stock
     outstanding on such record date, then, and in each such case, immediately
     after the close of business on such record date, the Conversion Rate shall
     be increased so that the same shall equal the Conversion Rate determined by
     multiplying the Conversion Rate in effect immediately prior to such record
     date by a fraction of which the numerator shall be such Average Closing
     Market Price and the denominator shall be such Average Closing Market Price
     less the amount of cash so distributed (and not excluded as provided above)
     applicable to one share of Common Stock, such increase to be effective
     immediately prior to the opening of business on the day following such
     record date; provided, however, that, if the portion of the cash so
     distributed applicable to one share of Common Stock is equal to or greater
     than the Average Closing Market Price on such record date, in lieu of the
     foregoing adjustment, adequate provision shall be made so that each Holder
     shall have the right to receive upon conversion the amount of cash such
     Holder would have received had such Holder converted such Security
     immediately prior to such record date. If such dividend or distribution is
     not so paid or made, the Conversion Rate shall again be adjusted to be the
     Conversion Rate which would then be in effect if such dividend or
     distribution had not been declared.

          (e) In case a tender offer made by the Company or any of its
     subsidiaries for all or any portion of any class of Common Stock expires
     and such tender offer (as amended upon the expiration thereof)
                                       38
<PAGE>   44

     requires the payment to stockholders (based on the acceptance (up to any
     maximum specified in the terms of the tender offer) of Purchased Shares (as
     defined below)) of an aggregate consideration having a fair market value
     (as determined by the Board of Directors, whose determination shall be
     conclusive and described in a resolution of the Board of Directors) that,
     combined together with (i) the aggregate of the cash plus the fair market
     value (as determined by the Board of Directors, whose determination shall
     be conclusive and described in a resolution of the Board of Directors), as
     of the expiration of such tender offer, of consideration payable in respect
     of any other tender offers, by the Company or any of its subsidiaries for
     all or any portion of any class of Common Stock expiring within the 12
     months preceding the expiration of such tender offer and in respect of
     which no adjustment pursuant to this Section 11.4(e) has been made, and
     (ii) the aggregate amount of any distributions to all holders of the Common
     Stock made exclusively in cash within 12 months preceding the expiration of
     such tender offer and in respect of which no adjustment pursuant to Section
     11.4(d) has been made, exceeds 10% of the product of the Average Closing
     Market Price as of the last time (the "Expiration Time") tenders could have
     been made pursuant to such tender offer (as it may be amended) and the
     number of shares of Common Stock outstanding (including any tendered
     shares) at the Expiration Time, then, and in each such case, immediately
     prior to the opening of business on the day after the date of the
     Expiration Time, the Conversion Rate shall be increased so that the same
     shall equal the Conversion Rate determined by multiplying the Conversion
     Rate in effect immediately prior to the Expiration Time by a fraction of
     which the numerator shall be the product of the number of shares of Common
     Stock outstanding (less any Purchased Shares) on the Expiration Time and
     the Common Stock Per Share Price on the Trading Day next succeeding the
     Expiration Time and the denominator shall be (x) the number of shares of
     Common Stock outstanding (including any tendered or exchanged shares) on
     the Expiration Time multiplied by Common Stock Per Share Price on the
     Trading Day next succeeding the Expiration Time less (y) the fair market
     value (determined as aforesaid) of the aggregate consideration payable to
     stockholders based on the acceptance (up to an maximum specified in the
     terms of the tender or exchanged offer) of all shares validly tendered or
     exchanged and not withdrawn as of the Expiration Time (the shares deemed so
     accepted, up to any such maximum, being referred to as the "Purchased
     Shares"), such increase to become effective immediately prior to the
     opening of business on the day following the Expiration Time. If the
     Company is obligated to purchase shares pursuant to any such tender offer,
     but the Company is permanently prevented by applicable law from effecting
     any such purchases or all such purchases are rescinded, the Conversion Rate
     shall again be adjusted to be the Conversion Rate which would then be in
     effect if such tender offer had not been made.

          (f) For purposes of this Section 11.4, the number of shares of Common
     Stock at any time outstanding shall not include shares held in the treasury
     of the Company but shall include shares issuable in respect of scrip
     certificates issued in lieu of fractions of shares of Common Stock. The
     Company shall not pay any dividend or make any distribution on shares of
     Common Stock held in the treasury of the Company.

          (g) To the extent permitted by applicable law, the Company from time
     to time may increase the Conversion Rate applicable to such series by any
     amount for any period of time if the period is at least 20 days, the
     increase is irrevocable during such period, and the Board of Directors
     shall have made a determination that such increase would be in the best
     interests of the Company, which determination shall be conclusive.

     Section 11.5. No Fractional Shares.

     No fractional shares or scrip representing fractional shares shall be
issued upon the conversion of any Security or Securities. If more than one
Security of any series shall be surrendered for conversion at one time by the
same Holder, the number of full shares issuable upon conversion thereof shall be
computed on the basis of the aggregate principal amount of the Securities of
such series so surrendered. If the conversion of any Security or Securities
results in a fraction, then the Holder of such Security or Securities shall be
required to make a cash payment to the Company in an amount sufficient to enable
the Holder to obtain a whole share in lieu of such fractional share.

                                       39
<PAGE>   45

     Section 11.6. Trustee Not Liable.

     The Trustee shall not at any time be under any duty or responsibility to
any Holder of Securities to determine whether any facts exist which may require
any adjustment of the Conversion Rate applicable thereto, or with respect to the
nature or extent of any such adjustment when made, or with respect to the method
employed, or to be employed, in making the same. The Trustee shall not be
accountable with respect to the validity or value (or the kind or amount) of any
shares of Common Stock or of any securities or property which may at any time be
issued or delivered upon the conversion of any Security, nor does it make any
representation with respect thereto. The Trustee shall not be responsible for
any failure of the Company to issue, transfer or deliver any shares of Common
Stock or stock certificates or other securities or other property upon the
surrender of any Security for the purpose of conversion, or, subject to Section
6.1, to comply with any of the covenants of the Company contained in this
Article XI.

                                  ARTICLE XII.

                             PRIORITY OF SECURITIES

     Section 12.1. Parity With All Unsecured Indebtedness.

     The indebtedness represented by the Securities and the payment of the
principal of and interest on each and all of the Securities are hereby expressly
made equal in right of payment to the payment of all other unsecured and
unsubordinated claims against and indebtedness of the Company.

     Section 12.2. Payment Over of Proceeds Upon Dissolution, Etc.

     In the event of (a) any insolvency or bankruptcy case or proceeding, or any
receivership, liquidation, reorganization or other similar case or proceeding in
connection therewith, relative to the Company or to its creditors, as such, or
to its assets, or (b) any liquidation, dissolution or other winding up of the
Company, whether voluntary or involuntary and whether or not involving
insolvency or bankruptcy, or (c) any assignment for the benefit of creditors or
any other marshalling of assets and liabilities of the Company, then and in any
such event the Holders shall be entitled to receive payment in full of all
amounts due or to become due on or in respect of all of the Securities, or
provision shall be made for such payment in money or money's worth, before the
stockholders of the Company are entitled to receive any distribution of the
assets of the Company.

     The consolidation of the Company with, or the merger of the Company into,
another Person or the liquidation or dissolution of the Company following the
conveyance or transfer of its properties and assets substantially as an entirety
to another Person shall not be deemed a dissolution, winding up, liquidation,
reorganization, assignment for the benefit of creditors or marshalling of assets
and liabilities of the Company for the purposes of this Section provided that
the Person formed by such consolidation or into which the Company is merged or
the Person which acquires by conveyance or transfer such properties and assets
substantially as an entirety, as the case may be, shall, as a part of such
consolidation, merger, conveyance or transfer, 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 principal and interest on all
the Securities and the performance of all covenants of the Indenture on the part
of the Company to be performed or observed.

                                       40
<PAGE>   46

     Section 12.3. Reliance on Judicial Order or Certificate of Liquidating
Agent.

     Upon any payment or distribution of assets of the Company referred to in
this Article, the Trustee, subject to the provisions of Section 6.1, and the
Holders of the Securities shall be entitled to rely upon any order or decree
entered by any court of competent jurisdiction in which such insolvency,
bankruptcy, receivership, liquidation, reorganization, dissolution, winding up
or similar case or proceeding is pending, or a certificate of trustee in
bankruptcy, receiver, liquidating trustee, custodian, assignee for the benefit
of creditors, agent or other Person making such payment or distribution,
delivered to the Trustee or to the Holders of Securities, for the purpose of
ascertaining the Persons entitled to participate in such payment or
distribution, the holders of other indebtedness of the Company, the amount
thereof or payable thereon, the amount or amounts paid or distributed thereon
and all other facts pertinent thereto or to this Article.

                                    *  *  *

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

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

                                          UNITED METRO MATERIALS INC.

                                          [SEAL]

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

                                          Attest:
                                          --------------------------------------
                                          Title:
                                          --------------------------------------

                                          UMB BANK, N.A.
                                          Trustee

                                          [SEAL]

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

                                          Attest:
                                          --------------------------------------
                                          Title:
                                          --------------------------------------

                                       41<PAGE>   1

                                                                     EXHIBIT 4.3

                   FORM OF SERIES 2000A CONVERTIBLE DEBENTURE
                            KIEWIT MATERIALS COMPANY
                             A DELAWARE CORPORATION

Registered Debenture No.                                $
8.028% Convertible Debenture                               Due: October 31, 2010

     KIEWIT MATERIALS COMPANY, a corporation organized and existing under the
laws of the State of Delaware, and having its principal place of business in the
City of Omaha, Nebraska (hereinafter called the "Corporation"), for the value
received, hereby promises to pay to                or registered assigns
(hereinafter called the "Debentureholder") on October 31, 2010, the principal
sum of                ($          ) Dollars.

     This debenture is one of the 2000A series of registered convertible
debentures of the Corporation, due October 31, 2010 unless previously redeemed
or converted, limited to the aggregate principal amount of                and
No/100 ($          ) Dollars, all issued or to be issued pursuant to an
indenture, dated as of             , 2000 (the "Indenture"), executed and
delivered by the Corporation and UMB Bank, N.A. as Trustee, (hereinafter
referred to as "Trustee"). This debenture is subject to the terms of the
Indenture, and all indentures supplemental thereto, and reference is hereby made
to the Indenture and any such supplemental indenture for a description of the
rights, limitations, obligations and immunities of the Corporation, the holders
of the debentures and the Trustee. Capitalized terms used and not defined herein
have the meanings ascribed to those terms in the Indenture.

          (1) TYPE OF PAYMENT:  Payment of interest and principal shall be in
     any coin or currency of the United States of America which at the time of
     payment shall be legal tender for the payment of public or private debts.

          (2) INTEREST:  Except as hereinafter provided, the Corporation
     promises to pay to the registered holder hereof or his registered assigns,
     interest on the principal sum of this debenture at the rate of eight and
     twenty eight thousandths percent (8.028%) per annum until the Corporation's
     obligation with respect to the payment of the principal amount shall have
     been discharged. Interest shall accrue upon this debenture from the most
     recent date to which interest has been paid, or if no interest has been
     paid, from the date of original issuance. In the event of conversion as
     provided in paragraph (7)(a) hereof, interest shall cease accruing on the
     principal amount of this debenture on June 30, 2002. In the event of
     conversion as provided in paragraph (7)(b) hereof, interest shall cease
     accruing on the principal amount of this debenture on the Conversion Date.
     Interest on this debenture shall be paid annually on each November 1st,
     commencing November 1, 2000.

          (3) PLACE OF PAYMENT:  The principal and interest on this debenture
     shall be payable at the office of the Corporation in Omaha, Nebraska.

          (4) DEFAULT:  This debenture shall be deemed to be in default whenever
     the principal sum and/or interest becomes payable and remains unpaid for a
     period of sixty (60) days.

          (5) REDEMPTION:  This debenture is subject to redemption at any time
     prior to the date of maturity at its principal amount plus all accrued and
     unpaid interest to the date of redemption, provided, however, that the
     entire series is redeemed. This debenture may not be redeemed during the
     thirty-one (31) day conversion period provided for in paragraph (7)(a)
     hereof. Redemption shall be preceded by notice thereof, mailed to the
     registered holder by registered mail no later than thirty (30) days
     preceding the date of redemption. The registered holder may convert this
     debenture into Common Stock during that thirty (30) day period preceding
     the date set for redemption as provided for in paragraph 7(b) hereof.

          (6) TRANSFER:  The debenture may be transferred by the registered
     holder at the principal office of the Corporation in Omaha, Nebraska on
     registry books kept for such purpose at such office, upon
<PAGE>   2

     surrender and cancellation of this debenture, and the payment of applicable
     charges. The Corporation and the Trustee may treat the registered holder of
     this debenture as the absolute owner for all purposes.

          (7) CONVERSION:

          (a) This debenture is convertible into the $0.01 par value common
     stock ("Common Stock") of the Corporation on the following basis: during
     the period commencing on October 1, 2002 and ending on October 31, 2002,
     the registered holder may convert the entire principal amount of this
     debenture, plus a cash payment equal to the product of
     multiplied by the Average Closing Market Price on the Conversion Date, into
                    (               ) shares of Common Stock, subject to
     adjustment upon the occurrence of certain events as provided in the
     Indenture.

          (b) If any of the following events occur prior to October 1, 2002,
     this debenture is convertible into Common Stock: (i) for thirty (30) days
     following the occurrence of the registered holder's death; (ii) for thirty
     (30) days following a Change of Control; and (iii) for thirty (30) days
     prior to redemption of the registered holder's debentures, as provided for
     in paragraph (5) hereof. During any such period, the registered holder or
     the registered holder's representative or estate, as the case may be, may
     convert the entire principal amount of the debenture plus a cash payment
     equal to the product of                multiplied by the Average Closing
     Market Price on the Conversion Date, into                (               )
     shares of Common Stock, subject to adjustment upon the occurrence of
     certain events as provided in the Indenture.

          (c) During the period commencing on November 1, 2002 and ending on
     October 31, 2010, the date of maturity, the debenture is not convertible,
     in whole or in part.

          (d) The conversion privilege shall be deemed exercised by submission
     of this debenture with a written request for conversion plus the required
     cash payment during the applicable conversion period at the principal
     office of the Corporation. The Corporation shall thereafter, within a sixty
     (60) day period, issue certificates registered in the name of the
     registered holder representing the shares of Common Stock into which this
     debenture has been converted.

          (8) SUBORDINATION:  In the payment of their claims, all creditors of
     the Corporation shall rank equally with the holders of convertible
     debentures. All claims of the debentureholders against earnings or assets
     are hereby made superior to those of stockholders, and the Corporation
     agrees that as long as any of its convertible debentures are outstanding,
     it will not pay any dividends on its stock until all liability for unpaid
     interest on its debentures has been paid. In the event of dissolution or
     liquidation of the Corporation, the holders of all debentures shall be
     entitled to be paid in full, both principal and interest, before any assets
     of the Corporation are distributed to any stockholder.

          (9) LIQUIDATION OF LIABILITY:  No recourse shall be had for the
     payment of the principal or interest of this debenture, against any
     incorporator, stockholder, officer, or director, past, present, or future,
     of the Corporation, all such liability being expressly waived by the owner
     of this debenture.

          (10) VALIDATION:  This debenture shall not be valid or become
     obligatory for any purpose until the certificate of authentication thereon
     shall have been signed by the Trustee.

                                        2
<PAGE>   3

     IN WITNESS WHEREOF, Kiewit Materials Company has caused this debenture to
become signed and its corporate seal to be hereunto affixed by its officers duly
authorized thereunto, all as of the      day of             , 2000.

<TABLE>
<S>                                                    <C>
ATTEST:                                                KIEWIT MATERIALS COMPANY

                                                       By
-----------------------------------------------------
Assistant Secretary                                    -----------------------------------------------------
                                                          President
</TABLE>

TRUSTEE'S CERTIFICATE OF AUTHENTICATION:  This is one of the debentures
described in the Trust Indenture, dated as of             , 2000, by and between
Kiewit Materials Company and UMB Bank, N.A. as Trustee.

<TABLE>
<S>                                                    <C>

Dated                                                  By
                                                       -----------------------------------------------------
-----------------------------------------------------     Authorized Officer
</TABLE>

This Debenture and the transfer thereof are subject to restrictions which are
stated in an Agreement between the Debentureholder(s) whose name(s) appear(s)
hereon and KIEWIT MATERIALS COMPANY, dated             , 2000.

                                        3

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