Document:

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                                                                     Exhibit 4.7

                                                                            1997

                            PETER KIEWIT SONS', INC.
                             a Delaware corporation

Registered Debenture No. ____________                       $ _________________
8.028% Convertible Debenture                              Due: October 31, 2007

     PETER KIEWIT SONS', INC., 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, 2007, the
principal sum of                        ($                 ) Dollars.

     This debenture is one of a 1997 issue of registered convertible debentures
of the Corporation, due October 31, 2007 unless previously redeemed or
converted, limited to the aggregate principal amount of **TEN MILLION**
($10,000,000) Dollars, all issued or to be issued pursuant to an indenture,
dated of July 1, 1986, executed and delivered by the Corporation to First Bank,
N.A. Omaha, Nebraska, a national banking association organized and existing
under the laws of the United States, as Trustee (hereinafter referred to as
Trustee). Reference is hereby made to the indenture, and all indentures
supplemental thereto, for a description of the rights, limitations, obligations
and immunities of the Corporation, the holders of the debentures and the
Trustee.

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.

INTEREST: Except as hereinafter provided, the Corporation promises to pay to
the registered owner hereof or his registered assigns, interest on the
principal sum as of November 1, 1998 and each succeeding November 1, at the rate
of Eight and twenty eight thousandths (8.028) percent 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 until the
date of redemption or maturity, whichever of these dates shall first occur. In
the event of conversion as provided in paragraph (7) hereof, interest shall
cease running on the principal amount of the debenture on June 30, 2002.
Interest on this debenture shall be paid annually on the November 1st
immediately following the twelve months in which such interest was earned.

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

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.

REDEMPTION: This debenture is subject to redemption at any time prior to the
date of maturity at its principal amount plus all 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) hereof. Redemption shall be preceded by notice
thereof, given to the registered holder by registered mail no later than ten
(10) days preceding the date of redemption.

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

CONVERSION: (a) This debenture is convertible into [the $0.01 par value common
stock ("Common Stock")] of the Corporation on the following basis: the
debenture is not convertible, in whole or in part, for the period commencing on
the date of issuance and ending on September 30, 2002. During the period
commencing on October 1, 2001 and ending on October 31, 2002, the
Debentureholder may convert the principal amount of the debenture plus a cash
payment in the amount of **NO** ($0.00) Dollars into      (               )
shares of [Common Stock] of the Corporation. During the period commencing on
November 1, 2002 and ending on
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October 31, 2007, the date of maturity, the debenture is not convertible, in
whole or in part. The conversion privilege shall be deemed exercised by
submission of the debenture with a written request for conversion during the
applicable thirty-one (31) day period at the principal office of the
Corporation. The Corporation shall thereafter, within a sixty (60) day period,
issue the [Common Stock] of the Corporation. As a condition precedent to the
rights of conversion granted in this paragraph, the Debentureholder agrees to
execute the applicable Peter Kiewit Sons', Inc. Stock Repurchase Agreement.

In case the Corporation shall change the stock issuable upon conversion into the
same or different number of new shares of the same or of any other class or
classes, the Debentureholder, upon conversion, shall be entitled to receive, in
lieu of the old stock which he would have been entitled to receive but for such
change, a number of shares of the new stock equivalent to the number of shares
of new stock that would have been issued to him in exchange for such number of
shares of old stock which he would have been entitled to receive if the
conversion privilege had been exercisable and exercised immediately prior to
such change.

In case at any time or from time to time the Corporation shall declare and pay
on or in respect of the class of stock issuable upon conversion, any dividend of
shares of stock of any class or classes, the Debentureholder, upon exercising
the conversion privilege, after the date of record of the holders of stock to
whom such stock dividend is payable, shall be entitled to receive the shares of
stock theretofore issuable upon conversion, together with the dividend stock
which would have been issuable if the conversion privilege had been exercisable
and exercised immediately prior to the record date.

The Corporation covenants and agrees that in case it shall consolidate or merge
with, or shall sell its property as an entirety, or substantially as an entirety
to any other corporation, proper provision will be made as part of the terms of
such consolidation, merger or sale, that the holder of any convertible debenture
will thereafter be entitled to convert it into the same kind and amount of
securities and any other assets as may be issuable or distributable by the terms
of such consolidation, merger or sale with respect to the number of shares of
[Common Stock] into which this debenture is convertible at the time of such
consolidation, merger or sale; provided, however, that the surviving corporation
with which the Corporation consolidates, merges or sells its property shall
succeed to all of the rights provided for in this debenture, including the right
of redemption.

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
convertible 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.

OWNERSHIP: The Corporation may treat the registered owner of the debenture as
the absolute owner of this debenture.

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.

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.

SHARE EXCHANGE PROVISIONS. The board of Directors of the Corporation has
unanimously approved a series of transactions intended to separate the
construction businesses of the Corporation and the diversified businesses of the
Corporation (the "Transaction"). In connection therewith, the Corporation and
its wholly owned subsidiary, PKS Holdings, Inc. ("PKS Holdings"), have filed a
Registration Statement on Form S-4 (Registration No. 333-34627) with the
Securities and Exchange Commission. In the event that the Transaction is
consummated, each issued and outstanding share of Class C Stock will be
mandatorily exchanged (the "Share Exchange") for one share of $.01 par value
common stock of PKS Holdings ("PKS Holdings Stock"). Immediately upon the
completion of the Share Exchange, this debenture shall, automatically, and
without further action by or on behalf of the

                                      -2-

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Corporation, PKS Holdings or the Debentureholder, be converted into a debenture
of PKS Holdings, convertible into the number of shares of PKS Holdings Stock as
it was previously convertible into Class C Stock, and the Corporation shall
thereafter have no further liability or obligation hereunder.

     IN WITNESS WHEREOF, Peter Kiewit Sons', Inc. 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 1st day of November, 1999.

ATTEST:   PETER KIEWIT SONS', INC.

___________________________________     By ________________________________
    Assistant Secretary                           President

TRUSTEE'S CERTIFICATE OF AUTHENTICATION: This is one of the debentures described
in the Trust Indenture, executed as of July 1, 1986, by and between the
Corporation and First Bank, N.A., as Trustee, as amended pursuant to a First
Supplemental Indenture between the Corporation, PKS and U.S. Bank National
Association, as successor trustee dated as of March 31, 1998.

     Dated ________________________     By _________________________________
                                                  Authorized Officer

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 PETER KIEWIT SONS', INC., dated November 1, 1997.

                                      -3-<PAGE>   1

                                                                    EXHIBIT 4.10

                   FORM OF SERIES 1997A CONVERTIBLE DEBENTURE
                            PETER KIEWIT SONS', INC.
                             A DELAWARE CORPORATION

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

     PETER KIEWIT SONS', INC., 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 1997A 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 July 1, 1986, executed and delivered by Peter Kiewit Sons', Inc.
(now Level 3 Communications, Inc.) ("PKS") and FirstTier Bank, N.A. Omaha, as
trustee, as amended pursuant to a First Supplemental Indenture between the
Corporation, PKS and U.S. Bank National Association (hereinafter referred to as
"Trustee"), as successor trustee dated as of March 31, 1998. Reference is hereby
made to the indenture, and all indentures supplemental thereto, for a
description of the rights, limitations, obligations and immunities of the
Corporation, the holders of the debentures and the Trustee.

          (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) hereof, interest shall cease accruing on the
     principal amount of the debenture on June 30, 2002. 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 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) hereof.
     Redemption shall be preceded by notice thereof, given to the registered
     holder by registered mail no later than ten (10) days preceding the date of
     redemption.

          (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
     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.
<PAGE>   2

        (7) CONVERSION:

          (a) This debenture is convertible into the $0.01 par value common
     stock ("Common Stock") of the Corporation on the following basis: the
     debenture is not convertible, in whole or in part, for the period
     commencing on the date of issuance and ending on September 30, 2002. During
     the period commencing on October 1, 2002 and ending on October 31, 2002,
     the registered holder may convert the entire principal amount of the
     debenture plus a cash payment in the amount of                multiplied by
     the formula value of the Common Stock on the date of conversion, into
                    (               ) shares of Common Stock of the Corporation.
     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. The conversion privilege shall be deemed exercised by submission
     of the debenture with a written request for conversion during the
     applicable thirty-one (31) day period at the principal office of the
     Corporation. The Corporation shall thereafter, within a sixty (60) day
     period, issue the Common Stock into which the debenture shall have been
     converted. As a condition precedent to the rights of conversion granted in
     this paragraph, the Debentureholder agrees to execute the Corporation's
     applicable Stock Repurchase Agreement. The debenture shall only be
     convertible by the registered holder if the registered holder is otherwise
     eligible to own shares of Common Stock of the Corporation as provided in
     the Corporation's Restated Certificate of Incorporation.

          (b) In case the Corporation shall change the stock issuable upon
     conversion into the same or different number of new shares of the same or
     of any other class or classes, the Debentureholder, upon conversion, shall
     be entitled to receive, in lieu of the old stock which he would have been
     entitled to receive but for such change, a number of shares of the new
     stock equivalent to the number of shares of new stock that would have been
     issued to him in exchange for such number of shares of old stock which he
     would have been entitled to receive if the conversion privilege had been
     exercisable and exercised immediately prior to such change.

          (c) In case at any time or from time to time the Corporation shall
     declare and pay on or in respect of the class of stock issuable upon
     conversion, any dividend of shares of stock of any class or classes, the
     Debentureholder, upon exercising the conversion privilege, after the date
     of record of the holders of stock to whom such stock dividend is payable,
     shall be entitled to receive the shares of stock theretofore issuable upon
     conversion, together with the dividend stock which would have been issuable
     if the conversion privilege had been exercisable and exercised immediately
     prior to the record date.

          (d) The Corporation covenants and agrees that in case it shall
     consolidate or merge with, or shall sell its property as an entirety, or
     substantially as an entirety to any other corporation, proper provision
     will be made as part of the terms of such consolidation, merger or sale,
     that the holder of any convertible debenture will thereafter be entitled to
     convert it into the same kind and amount of securities and any other assets
     as may be issuable or distributable by the terms of such consolidation,
     merger or sale with respect to the number of shares of Common Stock into
     which this debenture is convertible at the time of such consolidation,
     merger or sale; provided, however, that the surviving corporation with
     which the Corporation consolidates, merges or sells its property shall
     succeed to all of the rights provided for in this debenture, including the
     right of redemption.

          (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 convertible 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) OWNERSHIP:  The Corporation may treat the registered owner of the
     debenture as the absolute owner of this debenture.

                                        2
<PAGE>   3

          (10) 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.

          (11) 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, Peter Kiewit Sons', Inc. 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:                                                PETER KIEWIT SONS', INC.
-----------------------------------------------------  By --------------------------------------------------
Assistant Secretary                                    President
</TABLE>

TRUSTEE'S CERTIFICATE OF AUTHENTICATION:  This is one of the debentures
described in the Trust Indenture, dated as of July 1, 1986, by and between Peter
Kiewit Sons', Inc. (now Level 3 Communications, Inc.) ("PKS") and FirstTier
Bank, N.A. Omaha, as trustee, as amended pursuant to a First Supplemental
Indenture between the Corporation, PKS and U.S. Bank National Association, as
successor trustee dated as of March 31, 1998.

<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 PETER KIEWIT SONS', INC., dated November 1, 1997.

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