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                                                                     Exhibit 4.6

                          THIRD SUPPLEMENTAL INDENTURE

         THIRD SUPPLEMENTAL INDENTURE, dated as of December 21, 2001 (this
"Third Supplemental Indenture"), between NorthWestern Corporation, a Delaware
corporation (the "Company"), and JPMorgan Chase Bank (as successor to The Chase
Manhattan Bank), as trustee (the "Trustee") under the Indenture dated as of
August 1, 1995 between the Company and the Trustee (such Indenture, as
supplemented by the First Supplemental Indenture thereto dated as of August 1,
1995, as further supplemented by the Second Supplemental Indenture thereto dated
as of November 18, 1998, and as further supplemented by this Third Supplemental
Indenture, the "Indenture").

         WHEREAS, the Company executed and delivered the Indenture to the
Trustee to provide for the future issuance of the Company's subordinated debt
securities, to be issued from time to time in one or more series as might be
determined by the Company under the Indenture, in an unlimited aggregate
principal amount which may be authenticated and delivered as provided in the
Indenture;

         WHEREAS, pursuant to the terms of the Indenture, the Company desires to
provide for the establishment of a new series of its Securities to be known as
its 8 1/4% Junior Subordinated Deferrable Interest Debentures due December 15,
2031 (the "Subordinated Debentures"), the form and substance of such
Subordinated Debentures and the terms, provisions and conditions thereof to be
set forth as provided in the Indenture and this Third Supplemental Indenture;

         WHEREAS, NorthWestern Capital Financing II, a Delaware statutory
business trust (the "Trust"), has offered to the public $100,000,000 aggregate
liquidation amount of its 8 1/4% Trust Preferred Securities (the "Preferred
Securities") and has offered to the Company $3,092,800 in aggregate liquidation
amount of the Trust's common securities, each representing undivided beneficial
interests in the assets of the Trust, and proposes to invest the proceeds from
such offerings in $103,092,800 aggregate principal amount of the Subordinated
Debentures; and

         WHEREAS, the Trust has entered into an overallotment option (the
"Overallotment Option") in the Underwriting Agreement (the "Underwriting
Agreement") dated as of December 18, 2001, among the Company, the Trust and
Merrill Lynch & Co., Merrill Lynch, Pierce, Fenner & Smith Incorporated, Morgan
Stanley & Co. Incorporated and Salomon Smith Barney Inc., as representatives of
the several Underwriters named in Schedule A thereto, pursuant to which the
Preferred Securities are sold whereby the Trust, within 30 days after the
issuance of the Preferred Securities, may issue up to an additional $15,000,000
in aggregate liquidation amount of the Preferred Securities and an additional
$463,925 in aggregate liquidation amount of the Common Securities and proposes
to invest the proceeds from the Overallotment Option in an equivalent aggregate
principal amount of Subordinated Debentures; and

         WHEREAS, the Company has requested that the Trustee execute and deliver
this Third Supplemental Indenture, and all requirements necessary to make this
Third Supplemental Indenture a valid instrument in accordance with its terms
(and to make the Subordinated Debentures, when executed by the Company and
authenticated and delivered by the Trustee, the

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valid obligations of the Company) have been performed, and the execution and
delivery of this Third Supplemental Indenture has been duly authorized in all
respects.

         NOW THEREFORE, in consideration of the purchase and acceptance of the
Subordinated Debentures by the Holders thereof, and for the purpose of setting
forth, as provided in the Indenture, the form and substance of the Subordinated
Debentures and the terms, provisions and conditions thereof, the Company
covenants and agrees with the Trustee as follows:

                                   ARTICLE I
                                  DEFINITIONS

         SECTION 1.1. Definition of Terms.

         Unless the context otherwise requires:

                (a) a term not defined herein that is defined in the Indenture
has the same meaning when used in this Third Supplemental Indenture;

                (b) a term defined anywhere in this Third Supplemental Indenture
has the same meaning throughout;

                (c) the singular includes the plural and vice versa;

                (d) a reference to a Section or Article is to a Section or
Article of this Third Supplemental Indenture;

                (e) headings are for convenience of reference only and do not
affect interpretation;

                (f) the Trust shall be deemed to be an "NWPS Trust" for purposes
of the Indenture;

                (g) the following terms have the meanings given to them in the
Declaration: (i) Business Day; (ii) Clearing Agency; (iii) Delaware Trustee;
(iv) Distribution; (v) Property Trustee; (vi) Preferred Securities Guarantee;
(vii) Preferred Security Certificate; and (viii) Regular Trustees; and

                (h) the following terms have the meanings given to them in this
Section 1.1(h):

         "Additional Sums" has the meaning specified in Section 2.5(c).

         "Compounded Interest" has the meaning specified in Section 4.1.

         "Declaration" means the Amended and Restated Declaration of Trust of
the Trust, dated as of December 21, 2001, as amended or restated from time to
time.

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         "Direct Action" has the meaning specified in Section 10.2.

         "Dissolution Event" means that, as a result of the occurrence and
continuation of a Tax Event or an Investment Company Event or at the option of
the Company, the Trust is to be dissolved in accordance with the Declaration,
and the Subordinated Debentures held by the Property Trustee are to be
distributed to the holders of the Trust Securities issued by the Trust pro rata
in accordance with the Declaration.

         "Investment Company Event" means the receipt by the Trust of an opinion
of counsel to the Company experienced in such matters to the effect that, as a
result of the occurrence of an amendment to or a change in law or regulation or
a written change (including any announced prospective change) in law or
regulation or a change in interpretation or application of law or regulation by
any legislative body, court, governmental agency or regulatory authority, there
is more than an insubstantial risk that the Trust is or will be considered an
"investment company" that is required to be registered under the Investment
Company Act, which change or prospective change becomes effective or would
become effective, as the case may be, on or after the date of the issuance of
the Subordinated Debentures.

         "Maturity Date" has the meaning specified in Section 2.2.

         "Senior Indebtedness" means (i) the principal, premium, if any, and
interest in respect of (A) indebtedness of the Company for money borrowed and
(B) indebtedness evidenced by securities, debentures, bonds or other similar
instruments issued by the Company, including, without limitation, all
obligations under its General Mortgage and Deed of Trust dated as of August 1,
1993 between the Company and JPMorgan Chase Bank, as successor to The Chase
Manhattan Bank, as trustee, and the Indenture dated as of November 1, 1998
between the Company and JPMorgan Chase Bank, as trustee; (ii) all capital lease
obligations of the Company; (iii) all obligations of the Company issued or
assumed as the deferred purchase price of property, all conditional sale
obligations of the Company and all obligations of the Company under any title
retention agreement (but excluding trade accounts payable arising in the
ordinary course of business); (iv) all obligations of the Company for the
reimbursement on any letter of credit, banker's acceptance, security purchase
facility or similar credit transaction; (v) all obligations of the type referred
to in clauses (i) through (iv) of other Persons for the payment of which the
Company is responsible or liable as obligor, guarantor or otherwise; and (vi)
all obligations of the type referred to in clauses (i) through (v) of other
Persons secured by any lien on any property or asset of the Company (whether or
not such obligation is assumed by the Company), except for (a) any such
indebtedness that is by its terms subordinated to or pari passu with the
Subordinated Debentures and (b) any indebtedness between or among the Company
and its Affiliates, including all other debt securities and guarantees in
respect of those debt securities, issued to any other trust, or a trustee of
such trust, partnership or other entity affiliated with the Company which is a
financing vehicle of the Company ("Financing Entity") in connection with the
issuance by such Financing Entity of preferred securities or other securities
that rank pari passu with, or junior to, the Preferred Securities.

         "Tax Event" means the receipt by the Trust of an opinion of counsel to
the Company experienced in such matters to the effect that, as a result of any
amendment to, or change (including any announced prospective change) in, the
laws (or any regulations thereunder) of the

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United States or any political subdivision or taxing authority thereof or
therein, or as a result of any official or administrative pronouncement or
action or judicial decision interpreting or applying such laws or regulations,
which amendment or change is effective or which pronouncement, action or
decision is announced or occurs on or after the date of issuance of the
Subordinated Debentures, there is more than an insubstantial risk that (i) the
Trust is or will be within 90 days of the delivery of such opinion, subject to
United States federal income tax with respect to interest received or accrued on
the Subordinated Debentures, (ii) interest payable by the Company on the
Subordinated Debentures is not, or within 90 days of the delivery of such
opinion will not be, deductible by the Company, in whole or in part, for United
States federal income tax purposes, or (iii) the Trust is, or will be within 90
days of the delivery of such opinion, subject to more than a minimal amount of
other taxes, duties, assessments or other governmental charges.

                                   ARTICLE II
                 GENERAL TERMS AND CONDITIONS OF THE DEBENTURES

         SECTION 2.1. Designation and Principal Amount.

         There is hereby authorized a series of Securities designated the
"8 1/4% Junior Subordinated Deferrable Interest Debentures due December 15,
2031," limited in aggregate principal amount to $103,092,800, PROVIDED,
HOWEVER, that if the Overallotment Option is exercised, the aggregate
principal amount of the Subordinated Debentures may be increased to up to an
aggregate principal amount of $118,556,725, which amount shall be as set
forth in any written Company Order for the authentication and delivery of
Subordinated Debentures pursuant to Section 303 of the Indenture.

         SECTION 2.2. Maturity.

         The Scheduled Maturity Date will be December 15, 2031.

         SECTION 2.3. Form and Payment.

         Except as provided in Section 2.4, the Subordinated Debentures shall be
issued as Registered Securities in fully registered certificated form without
interest coupons. Principal of and interest on the Subordinated Debentures
issued in certificated form will be payable, the transfer of such Subordinated
Debentures will be registrable and such Subordinated Debentures will be
exchangeable for Subordinated Debentures bearing identical terms and provisions
at the office or agency of the Trustee; PROVIDED, HOWEVER, that payment of
interest may be made at the option of the Company by check mailed to the Holder
at such address as shall appear in the Security Register. Notwithstanding the
foregoing, so long as the Holder of any Subordinated Debentures is the Property
Trustee, the payment of the principal of and interest (including Compounded
Interest and Additional Sums, if any) on such Subordinated Debentures held by
the Property Trustee will be made at such place and to such account as may be
designated by the Property Trustee.
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         SECTION 2.4. Global Debenture.

                (a) In connection with a Dissolution Event:

                  (i)      The Subordinated Debentures in certificated form may
                           be presented to the Trustee by the Property Trustee
                           in exchange for a global Subordinated Debenture in an
                           aggregate principal amount equal to all Outstanding
                           Subordinated Debentures (a "Global Debenture"), to be
                           registered in the name of The Depository Trust
                           Company (the "Depository"), or its nominee, and
                           delivered by the Trustee to the Depository or a
                           custodian appointed by the Depository for crediting
                           to the accounts of its participants pursuant to the
                           instructions of the Regular Trustees. The Company
                           upon any such presentation shall execute a Global
                           Debenture in such aggregate principal amount and
                           deliver the same to the Trustee for authentication
                           and delivery in accordance with the Indenture and
                           this Third Supplemental Indenture. Payments on the
                           Subordinated Debentures issued as a Global Debenture
                           will be made to the Depository.

                  (ii)     If any Preferred Securities are held in non
                           book-entry certificated form, the Subordinated
                           Debentures in certificated form may be presented to
                           the Trustee by the Property Trustee, and any
                           Preferred Security Certificate which represents
                           Preferred Securities other than Preferred Securities
                           held by the Depository or its nominee ("Non
                           Book-Entry Preferred Securities") will be deemed to
                           represent beneficial interests in Subordinated
                           Debentures presented to the Trustee by the Property
                           Trustee having an aggregate principal amount equal to
                           the aggregate liquidation amount of the Non
                           Book-Entry Preferred Securities until such Preferred
                           Security Certificates are presented to the Security
                           Registrar for transfer or reissuance, at which time
                           such Preferred Security Certificates will be canceled
                           and a Subordinated Debenture registered in the name
                           of the holder of the Preferred Security Certificate
                           or the transferee of the holder of such Preferred
                           Security Certificate, as the case may be, with an
                           aggregate principal amount equal to the aggregate
                           liquidation amount of the Preferred Security
                           Certificate canceled will be executed by the Company
                           and delivered to the Trustee for authentication and
                           delivery in accordance with the Indenture and this
                           Third Supplemental Indenture. On issue of such
                           Subordinated Debentures, Subordinated Debentures with
                           an equivalent aggregate principal amount that were
                           presented by the Property Trustee to the Trustee will
                           be deemed to have been canceled.

                (b) A Global Debenture may be transferred, in whole but not in
part, only by the Depository to a nominee of the Depository, by a nominee of the
Depository to

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another nominee of the Depository, or by the Depository or such nominee to a
successor Depository selected or approved by the Company or to a nominee of such
successor Depository.

                (c) If at any time the Depository notifies the Company that it
is unwilling or unable to continue as Depository for the Subordinated Debentures
or if at any time the Depository ceases to be a clearing agency registered under
the Securities Exchange Act of 1934, as amended, or other applicable statute or
regulation, at a time the Depository is required to be so registered, and a
successor Depository is not appointed by the Company within 90 days after the
Company receives such notice or becomes aware of such condition, as the case may
be, the Company will execute, and, subject to Article Two of the Indenture, the
Trustee will authenticate and deliver, the Subordinated Debentures in definitive
registered form without coupons, in authorized denominations, and in an
aggregate principal amount equal to the principal amount of the Global Debenture
in exchange for such Global Debenture. In addition, if at any time the Company
determines that the Subordinated Debentures shall no longer be represented by a
Global Debenture or there shall have occurred an Event of Default, the Company
will execute, and, subject to receipt of a certificate evidencing such
determination by the Company, the Trustee will authenticate and deliver, the
Subordinated Debentures in definitive registered form without coupons, in
authorized denominations, and in an aggregate principal amount equal to the
principal amount of the Global Debenture in exchange for such Global Debenture.
Upon the exchange of the Global Debenture for such Subordinated Debentures in
definitive registered form without coupons, in authorized denominations, the
Global Debenture shall be canceled by the Trustee. Such Subordinated Debentures
in definitive registered form issued in exchange for the Global Debenture shall
be registered in such names and in such authorized denominations as the
Depository, pursuant to instructions from its direct or indirect participants or
otherwise, shall instruct the Trustee. The Trustee shall deliver such Securities
to the Depository for delivery to the Persons in whose names such Securities are
so registered.

         SECTION 2.5. Interest.

                (a) Each Subordinated Debenture will bear interest at the rate
of 8 1/4% per annum (the "Coupon Rate") from its original date of issuance or
from the most recent Interest Payment Date (as defined below) to which interest
has been paid or duly provided for until the principal thereof becomes due and
payable, and on any overdue principal and (to the extent that payment of such
interest is enforceable under applicable law) on any overdue installment of
interest at the Coupon Rate, compounded quarterly, payable (subject to the
provisions of Article Four) quarterly in arrears on March 15, June 15, September
15 and December 15 of each year (each, an "Interest Payment Date"), commencing
on March 15, 2002, to the Person in whose name such Subordinated Debenture or
any Predecessor Security is registered, at the close of business on the Regular
Record Date for such interest installment, which, in respect of any Subordinated
Debentures of which the Property Trustee is the Holder or a Global Debenture,
shall be the close of business on the Business Day next preceding that Interest
Payment Date; PROVIDED, HOWEVER, that interest paid at maturity shall be paid to
the Person to whom principal is paid. Notwithstanding the foregoing sentence, if
the Preferred Securities are no longer in book-entry only form or if pursuant to
the Indenture the Subordinated Debentures are not represented by a Global
Debenture, the Regular Record Date for such interest installment shall be 15
Business Days before the relevant Interest Payment Date. Any interest on

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any Subordinated Debenture which is payable but is not punctually paid or duly
provided for on any Interest Payment Date shall forthwith cease to be payable to
the Holder on the relevant Regular Record Date by virtue of having been such
Holder, and such defaulted interest and interest on such defaulted interest (to
the extent lawful) at the Coupon Rate may be paid by the Company, at its
election, (i) to the Persons in whose names the Subordinated Debentures (or
their respective Predecessor Securities) are registered at the close of business
on a Special Record Date to be fixed by the Company for such payment, notice of
which shall be not more than 15 days and not less than 10 days prior to the date
of the proposed payment, or (ii) in any other lawful manner not inconsistent
with the requirements of any securities exchange on which the Subordinated
Debentures may be listed, and upon such notice as may be required by such
exchange, all as more fully provided in Section 307 of the Indenture.

                (b) The amount of interest payable for any period will be
computed on the basis of a 360-day year of twelve 30-day months. Except as
provided in the following sentence, the amount of interest payable for any
period shorter than a full quarterly period for which interest in computed will
be computed on the basis of the actual number of days elapsed in such a 30-day
month. In the event that any date on which interest is payable on the
Subordinated Debentures is not a Business Day, then payment of interest payable
on such date will be made on the next succeeding day which is a Business Day
(and without any interest or other payment in respect of any such delay), except
that, if such Business Day is in the next succeeding calendar year, such payment
shall be made on the immediately preceding Business Day, in each case with the
same force and effect as if made on such date.

                (c) If, at any time while the Property Trustee is the Holder of
any Subordinated Debentures, the Trust or the Property Trustee is required to
pay any taxes, duties, assessments or governmental charges of whatever nature
(other than withholding taxes) imposed by the United States or any other taxing
authority (including, without limitation, if an event described in clause (i) or
(iii) of the definition of Tax Event has occurred and is continuing), then, in
any case, the Company will pay as additional interest ("Additional Sums") on the
Subordinated Debentures held by the Property Trustee such additional amounts as
shall be required so that the net amounts received and retained by the Trust and
the Property Trustee after paying such taxes, duties, assessments or other
governmental charges will be equal to the amounts the Trust and the Property
Trustee would have received had no such taxes, duties, assessments or other
government charges been imposed.

                                  ARTICLE III
                          REDEMPTION OF THE DEBENTURES

         SECTION 3.1. Special Event Redemption.

         If, prior to December 21, 2006, a Tax Event or an Investment Company
Event has occurred and is continuing then, notwithstanding Section 3.2, the
Company shall have the right upon not less than 30 nor more than 60 days' notice
to the Holders of the Subordinated Debentures to redeem the Subordinated
Debentures in whole (but not in part) within 90 days following the occurrence of
such Tax Event or Investment Company Event at a redemption price equal to 100%
of the principal amount to be redeemed plus any accrued and unpaid interest
thereon (including Compounded Interest and Additional Sums, if any) to the date
of such

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redemption (the "Redemption Price"). The Redemption Price shall be paid prior to
12:00 noon, New York time, on the date of such redemption or such earlier time
as the Company determines, provided that the Company shall have deposited with
the Trustee an amount sufficient to pay the Redemption Price by 10:00 a.m. on
the date such Redemption Price is to be paid. Such redemption shall otherwise be
in accordance with the provisions of Article Eleven of the Indenture.

         SECTION 3.2. Optional Redemption by Company.

                (a) Subject to the provisions of Section 3.2(b) and to the
provisions of Article Eleven of the Indenture, except as otherwise may be
specified in this Third Supplemental Indenture, the Company shall have the right
to redeem the Subordinated Debentures, in whole or in part, from time to time,
on or after December 21, 2006 at the Redemption Price. Any redemption pursuant
to this paragraph will be made upon not less than 30 nor more than 60 days'
notice to the Holder of the Subordinated Debentures. If the Subordinated
Debentures are only partially redeemed pursuant to this Section 3.2, the
particular Subordinated Debentures to be redeemed will be selected on a pro rata
basis by such method as the Trustee shall deem fair and appropriate or, if at
the time of redemption the Subordinated Debentures are registered as a Global
Debenture, in accordance with the Depository's customary procedures. The
Redemption Price shall be paid prior to 12:00 noon, New York time, on the date
of such redemption or at such earlier time as the Company determines, provided
that the Company shall have deposited with the Trustee an amount sufficient to
pay the Redemption Price by 10:00 a.m. on the date such Redemption Price is to
be paid.

                (b) The Company may not redeem fewer than all of the
Subordinated Debentures unless all accrued and unpaid interest has been paid on
all Subordinated Debentures for all quarterly interest payment periods
terminating on or prior to the date of redemption. If a partial redemption of
the Subordinated Debentures would result in the delisting of the Preferred
Securities issued by the Trust from any national securities exchange or other
organization on which the Preferred Securities are then listed, the Company
shall not be permitted to effect such partial redemption and may only redeem the
Subordinated Debentures in whole.

         SECTION 3.3. No Sinking Fund.

         The Subordinated Debentures are not entitled to the benefit of any
sinking fund.

                                   ARTICLE IV
                      EXTENSION OF INTEREST PAYMENT PERIOD

         SECTION 4.1. Extension of Interest Payment Period.

         So long as no Event of Default has occurred and is continuing, the
Company shall have the right, at any time during the term of the Subordinated
Debentures, from time to time to defer payments of interest by extending the
interest payment period of such Subordinated Debentures for up to 20 consecutive
quarters, but not beyond the Maturity Date of the Subordinated Debentures (the
"Extended Interest Payment Period"). To the extent permitted by applicable law,
interest, the payment of which has been deferred because of the extension of the
interest payment

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period pursuant to this Section 4.1, will bear interest thereon at the Coupon
Rate compounded quarterly for each quarter of the Extended Interest Payment
Period ("Compounded Interest"). At the end of the Extended Interest Payment
Period the Company shall pay all interest accrued and unpaid on the Subordinated
Debentures, including any Additional Sums and Compounded Interest ("Deferred
Interest") that shall be payable, to the Holders of the Subordinated Debentures
in whose names the Subordinated Debentures are registered in the Security
Register on the first Regular Record Date after the end of the Extended Interest
Payment Period. Before the termination of any Extended Interest Payment Period,
the Company may further extend such period, provided that such period together
with all such previous and further extensions thereof shall not exceed 20
consecutive quarters or extend beyond the Maturity Date. Upon the termination of
any Extended Interest Payment Period and upon the payment of all Deferred
Interest then due, the Company may commence a new Extended Interest Payment
Period, subject to the foregoing requirements. No interest shall be due and
payable during an Extended Interest Payment Period, except at the end thereof.

         SECTION 4.2. Notice of Extension.

                (a) If the Property Trustee is the only registered Holder of the
Subordinated Debentures at the time the Company selects an Extended Interest
Payment Period, the Company shall give written notice to the Regular Trustees,
the Property Trustee and the Trustee of its selection of such Extended Interest
Payment Period one Business Day before the earlier of (i) the next succeeding
date on which Distributions on the Trust Securities issued by the Trust are
payable, or (ii) the date the Trust is required to give notice of the record
date or the date such Distributions are payable to the New York Stock Exchange
or other applicable self-regulatory organization or to holders of the Preferred
Securities issued by the Trust, but in any event at least one Business Day
before such record date.

                (b) If the Property Trustee is not the only Holder of the
Subordinated Debentures at the time the Company selects an Extended Interest
Payment Period, the Company shall give the Holders of the Subordinated
Debentures and the Trustee written notice of its selection of such Extended
Interest Payment Period 10 Business Days before the earlier of (i) the next
succeeding Interest Payment Date, or (ii) the date the Company is required to
give notice of the record or payment date of such interest payment to the New
York Stock Exchange or other applicable self-regulatory organization or to
Holders of the Subordinated Debentures.

                (c) The quarter in which any notice is given pursuant to
paragraphs (a) or (b) of this Section 4.2 shall be counted as one of the 20
quarters permitted in the maximum Extended Interest Payment Period permitted
under Section 4.1.

         SECTION 4.3. Restrictions on Payments.

         So long as any Subordinated Debentures remain outstanding, if there
shall have occurred an Event of Default (as defined in the Indenture), or an
event of which the Company has actual knowledge that, with the giving of notice
or the lapse of time or both, would constitute an Event of Default under the
Indenture and in respect of which the Company shall not have taken reasonable
steps to cure or the Company is in default with respect to the payment of any
obligations under the Preferred Securities Guarantee, or if the Company has
given notice of its

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selection of an Extended Interest Payment Period with respect to the
Subordinated Debentures pursuant to Section 4.1 hereof and shall not have
rescinded such notice, or such Excluded Interest Payment Period, or any
extension thereof, is continuing, then, in each case, (a) the Company shall not
declare or pay any dividend on, or make any distribution with respect to, or
redeem, purchase, acquire or make a liquidation payment with respect to, any of
its capital stock, (b) the Company shall not make any payment of interest,
principal or premium, if any, on or repay, repurchase or redeem any debt
securities (including guarantees of indebtedness for money borrowed) issued by
the Company which rank pari passu with or junior to the Subordinated Debentures,
and (c) the Company shall not make any payments with respect to any guarantee of
a debt security of any of the Company's subsidiaries (including other
guarantees) if such guarantee ranks pari passu with or junior to the
Subordinated Debentures; provided that the foregoing restrictions in this
Section 4.3 shall not apply to (i) repurchases, redemptions or other
acquisitions of shares of capital stock of the Company (A) in connection with
any employment contract, benefit plan or other similar arrangement with or for
the benefit of any one or more employees, officers, directors or consultants or
(B) in connection with a dividend reinvestment or stockholder stock purchase
plan, (ii) the issuance of common stock of the Company (or securities
convertible into or exercisable for such common stock) as consideration in an
acquisition transaction entered into prior to such Extended Interest Payment
Period, (iii) the reclassification of the capital stock of the Company or the
exchange or conversion of any class or series of the Company's capital stock for
another class or series of the Company's capital stock, provided that such
reclassification, exchange or conversion does not include any cash payments,
(iv) the purchase of fractional interests in shares of the Company's capital
stock pursuant to the conversion or exchange provisions of such capital stock or
the security being converted or exchanged, (v) the issuance of the capital stock
of the Company in connection with the exercise of certain rights on convertible
securities, (vi) any dividend in the form of common stock, warrants, options or
other rights where the dividend stock or the stock issuable upon exercise of
such warrants, options or other rights is common stock, or (vii) payments by the
Company under the Preferred Securities Guarantee or under any similar guarantee
by the Company with respect to any securities of its subsidiaries that are made
on a pro rata basis on all such guarantees, provided the proceeds from the
issuance of such securities were used to purchase Subordinated Debentures.

                                   ARTICLE V
                                    EXPENSES

         SECTION 5.1. Payment of Expenses.

         In connection with the offering, sale and issuance of the Subordinated
Debentures to the Property Trustee in connection with the sale of the Trust
Securities by the Trust, the Company shall:

                (a) pay for all costs and expenses relating to the offering,
sale and issuance of the Subordinated Debentures, including commissions to the
underwriters payable pursuant to the Underwriting Agreement and compensation of
the Trustee under the Indenture in accordance with the provisions of Section 607
of the Indenture; and
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                (b) pay for all costs and expenses of the Trust, including, but
not limited to, costs and expenses relating to the organization of the Trust,
the offering, sale and issuance of the Trust Securities (including commissions
to the underwriters payable pursuant to the Underwriting Agreement in connection
therewith); the fees and expenses of the Property Trustee (including, without
limitation, those incurred in connection with the enforcement by the Property
Trustee of the rights of the holders of the Preferred Securities), the Delaware
Trustee and the Regular Trustees; the costs and expenses relating to the
operation of the Trust (including, without limitation, costs and expenses of
accountants, attorneys, statistical or bookkeeping services, expenses for
printing and engraving and computing or accounting equipment, paying agent(s),
registrar(s), transfer agent(s), duplicating, travel and telephone and other
telecommunications expenses); and costs and expenses incurred in connection with
the acquisition, financing and disposition of Trust assets; and

                (c) pay any and all taxes (other than United States
withholding taxes attributable to the Trust or its assets) and all
liabilities, costs and expenses with respect to such taxes of the Trust.

                                   ARTICLE VI
                                  SUBORDINATION

         SECTION 6.1. Agreement to Subordinate.

         The Company covenants and agrees, and each Holder of Subordinated
Debentures issued hereunder by such Holder's acceptance thereof likewise
covenants and agrees, that all Subordinated Debentures shall be issued subject
to the provisions of this Article Six; and each Holder of a Subordinated
Debenture, whether upon original issue or upon transfer or assignment thereof,
accepts and agrees to be bound by such provisions. The payment by the Company of
the principal of and premium, if any, and interest on all Subordinated
Debentures issued hereunder shall, to the extent and in the manner hereinafter
set forth, be subordinated and junior in right of payment to the prior payment
in full of all Senior Indebtedness, whether outstanding at the date of this
Supplemental Indenture or hereafter incurred. No provision of this Article Six
shall prevent the occurrence of any default or Event of Default.

         SECTION 6.2. Default on Senior Indebtedness.

         In the event and during the continuation of any default by the Company
in the payment of principal, premium, interest or any other payment due on any
Senior Indebtedness, or in the event that any applicable grace period with
respect to such default has ended and such default has not been cured or waived
or ceased to exist, or in the event that the maturity of any Senior Indebtedness
has been accelerated because of a default, then, in either case, no payment
shall be made by the Company with respect to the principal (including redemption
and sinking fund payments) of, or premium, if any, or interest on the
Subordinated Debentures. In the event that, notwithstanding the foregoing, any
payment shall be received by the Trustee when such payment is prohibited by the
preceding paragraph of this Section 6.2, such payment shall be held in trust for
the benefit of, and shall be paid over or delivered to, the holders of such
Senior Indebtedness or their respective representatives, or to the trustee or
trustees under any indenture pursuant to which any Senior Indebtedness may have
been issued, as their respective interests may appear,

<Page>

but only to the extent that the holders of such Senior Indebtedness (or their
representative or representatives or a trustee) notify the Trustee in writing
within 90 days of such payment of the amounts then due and owing on such Senior
Indebtedness, and only the amounts specified in such notice to the Trustee shall
be paid to the holders of such Senior Indebtedness.

         SECTION 6.3. Liquidation; Dissolution; Bankruptcy.

         Upon any payment by the Company or distribution of assets of the
Company of any kind or character, whether in cash, property or securities, to
creditors upon any dissolution or winding-up or liquidation or reorganization of
the Company, whether voluntary or involuntary or in bankruptcy, insolvency,
receivership or other proceedings, all amounts due upon all Senior Indebtedness
shall first be paid in full, or payment thereof provided for in money in
accordance with its terms, before any payment is made by the Company on account
of the principal (and premium, if any) or interest on the Subordinated
Debentures; and upon any such dissolution or winding-up or liquidation or
reorganization, any payment by the Company, or distribution of assets of the
Company of any kind or character, whether in cash, property or securities, which
the Holders of the Subordinated Debenture or the Trustee would be entitled to
receive from the Company, except for the provisions of this Article Six, shall
be paid by the Company or by any receiver, trustee in bankruptcy, liquidating
trustee, agent or other Person making such payment or distribution, or by the
Holders of the Subordinated Debentures or by the Trustee under the Indenture if
received by them or it, directly to the holders of any Senior Indebtedness (pro
rata to such holders on the basis of the respective amounts of Senior
Indebtedness held by such holders, as calculated by the Company) or their
representative or representatives, or to the trustee or trustees under any
indenture pursuant to which any instruments evidencing such Senior Indebtedness
may have been issued, as their respective interests may appear, to the extent
necessary to pay such Senior Indebtedness in full, in money or money's worth,
after giving effect to any concurrent payment or distribution to or for the
holders of such Senior Indebtedness, before any payment or distribution is made
to the Holders of Subordinated Debentures or to the Trustee.

         In the event that, notwithstanding the foregoing, any payment or
distribution of assets of the Company of any kind or character, whether in cash,
property or securities, prohibited by the foregoing, shall be received by the
Trustee before all Senior Indebtedness is paid in full, or provision is made for
such payment in money in accordance with its terms, such payment or distribution
shall be held in trust for the benefit of and shall be paid over or delivered to
the holders of such Senior Indebtedness or their representative or
representatives, or to the trustee or trustees under any indenture pursuant to
which any instruments evidencing such Senior Indebtedness may have been issued,
as their respective interests may appear, as calculated by the Company, for
application to the payment of all Senior Indebtedness remaining unpaid to the
extent necessary to pay such Senior Indebtedness in full in money in accordance
with its terms, after giving effect to any concurrent payment or distribution to
or for the holders of such Senior Indebtedness.

         For purposes of this Article Six, the words "cash, property or
securities" shall not be deemed to include shares of stock of the Company as
reorganized or readjusted, or securities of the Company or any other corporation
provided for by a plan of reorganization or readjustment, the payment of which
is subordinated at least to the extent provided in this Article Six with

<Page>

respect to the Subordinated Debentures to the payment of all Senior Indebtedness
that may at the time be outstanding, provided that (i) such Senior Indebtedness
is assumed by the new corporation, if any, resulting from any such
reorganization or readjustment, and (ii) the rights of the holders of such
Senior Indebtedness are not, without the consent of such holders, altered by
such reorganization or readjustment. The consolidation of the Company with, or
the merger of the Company into, another corporation or the liquidation or
dissolution of the Company following the conveyance or transfer of its property
as an entirety, or substantially as an entirety, to another corporation upon the
terms and conditions provided for in Article Eight of the Indenture shall not be
deemed a dissolution, winding-up, liquidation or reorganization for the purposes
of this Section 6.3 if such other corporation shall, as a part of such
consolidation, merger, conveyance or transfer, comply with the conditions stated
in Article Eight of the Indenture. Nothing in Section 6.2 or in this Section 6.3
shall apply to claims of, or payments to, the Trustee under or pursuant to
Section 606 of the Indenture.

         SECTION 6.4. Subrogation.

         Subject to the payment in full of all Senior Indebtedness, the rights
of the Holders of the Subordinated Debentures shall be subrogated to the rights
of the holders of such Senior Indebtedness to receive payments or distributions
of cash, property or securities of the Company, as the case may be, applicable
to such Senior Indebtedness until the principal of (and premium, if any) and
interest on the Subordinated Debentures shall be paid in full; and, for the
purposes of such subrogation, no payments or distributions to the holders of
such Senior Indebtedness of any cash, property or securities to which the
Holders of the Subordinated Debentures or the Trustee would be entitled except
for the provisions of this Article Six, and no payment over pursuant to the
provisions of this Article Six to or for the benefit of the holders of such
Senior Indebtedness by Holders of the Subordinated Debentures or the Trustee
shall, as between the Company, its creditors other than holders of Senior
Indebtedness and the Holders of the Subordinated Debentures, be deemed to be a
payment by the Company to or on account of such Senior Indebtedness. It is
understood that the provisions of this Article Six are and are intended solely
for the purposes of defining the relative rights of the Holders of the
Subordinated Debentures, on the one hand, and the holders of such Senior
Indebtedness on the other hand.

         Nothing contained in this Article Six or elsewhere in the Indenture or
in the Subordinated Debentures is intended to or shall impair, as between the
Company, its creditors other than the holders of Senior Indebtedness and the
Holders of the Subordinated Debentures, the obligation of the Company, which is
absolute and unconditional, to pay to the Holders of the Subordinated Debentures
the principal of (and premium, if any) and interest on the Subordinated
Debentures as and when the same shall become due and payable in accordance with
their terms, or is intended to or shall affect the relative rights of the
Holders of the Subordinated Debentures and creditors of the Company, other than
the holders of Senior Indebtedness, nor shall anything herein or therein prevent
the Trustee or the Holder of any Subordinated Debenture from exercising all
remedies otherwise permitted by applicable law upon default under the Indenture,
subject to the rights, if any, under this Article Six of the holders of such
Senior Indebtedness in respect of cash, property or securities of the Company
received upon the exercise of any such remedy. Upon any payment or distribution
of assets of the Company referred to in this Article Six, the Trustee, subject
to the provisions of Section 602 of the Indenture, and the Holders of the
Subordinated Debentures shall be entitled to rely upon any order or decree made
by any court of

<Page>

competent jurisdiction in which such dissolution, winding-up, liquidation or
reorganization proceedings are pending, or a certificate of the receiver,
trustee in bankruptcy, liquidation trustee, agent or other Person making such
payment or distribution, delivered to the Trustee or to the Holders of the
Subordinated Debentures, for the purposes of ascertaining the Persons entitled
to participate in such distribution, the holders of Senior Indebtedness and
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 Six.

         SECTION 6.5. Trustee to Effectuate Subordination.

         Each Holder of Subordinated Debentures by such Holder's acceptance
thereof authorizes and directs the Trustee on such Holder's behalf to take such
action as may be necessary or appropriate to effectuate the subordination
provided in this Article Six and appoints the Trustee such Holder's
attorney-in-fact for any and all such purposes.

         SECTION 6.6. Notice by the Company.

         The Company shall give prompt written notice to a Responsible Officer
of the Trustee of any fact known to the Company that would prohibit the making
of any payment of monies to or by the Trustee in respect of the Subordinated
Debentures pursuant to the provisions of this Article Six. Notwithstanding the
provisions of this Article Six or any other provision of the Indenture and this
Third Supplemental Indenture, the Trustee shall not be charged with knowledge of
the existence of any facts that would prohibit the making of any payment of
monies to or by the Trustee in respect of the Subordinated Debentures pursuant
to the provisions of this Article Six, unless and until a Responsible Officer of
the Trustee shall have received written notice thereof from the Company or a
holder or holders of Senior Indebtedness or from any trustee therefor; and
before the receipt of any such written notice, the Trustee, subject to the
provisions of Section 602 of the Indenture, shall be entitled in all respects to
assume that no such facts exist; PROVIDED, HOWEVER, that, if the Trustee shall
not have received the notice provided for in this Section 6.6 at least two
Business Days prior to the date upon which by the terms hereof any money may
become payable for any purpose (including, without limitation, the payment of
the principal of (or premium, if any) or interest on any Subordinated
Debenture), then, anything herein contained to the contrary notwithstanding, the
Trustee shall have full power and authority to receive such money and to apply
the same to the purposes for which they were received, and shall not be affected
by any notice to the contrary that may be received by it within two Business
Days prior to such date.

         The Trustee, subject to the provisions of Section 602 of the Indenture,
shall be entitled to rely on the delivery to it of a written notice by a Person
representing himself to be a holder of Senior Indebtedness (or a trustee on
behalf of such holder) to establish that such notice has been given by a holder
of such Senior Indebtedness or a trustee on behalf of any such holder or
holders. In the event that the Trustee determines in good faith that further
evidence is required with respect to the right of any Person as a holder of such
Senior Indebtedness to participate in any payment or distribution pursuant to
this Article Six, the Trustee may request such Person to furnish evidence to the
reasonable satisfaction of the Trustee as to the amount of such Senior
Indebtedness held by such Person, the extent to which such Person is entitled to
participate in such payment or distribution and any other facts pertinent to the
rights of such Person under this

<Page>

Article Six, and, if such evidence is not furnished, the Trustee may defer any
payment to such Person pending judicial determination as to the right of such
Person to receive such payment.

         SECTION 6.7. Rights of the Trustee; Holders of Senior Indebtedness.

         The Trustee in its individual capacity shall be entitled to all the
rights set forth in this Article Six in respect of any Senior Indebtedness at
any time held by it, to the same extent as any other holder of Senior
Indebtedness, and nothing in this Indenture shall deprive the Trustee of any of
its rights as such holder.

         With respect to the holders of Senior Indebtedness, the Trustee
undertakes to perform or to observe only such of its covenants and obligations
as are specifically set forth in this Article Six, and no implied covenants or
obligations with respect to the holders of such Senior Indebtedness shall be
read into this Indenture against the Trustee. The Trustee shall not be deemed to
owe any fiduciary duty to the holders of such Senior Indebtedness, and the
Trustee shall not be liable to any holder of such Senior Indebtedness if it
shall mistakenly pay over or deliver to the Holders of the Subordinated
Debentures, the Company or any other Person money or assets to which any holder
of such Senior Indebtedness shall be entitled by virtue of this Article Six or
otherwise.

         SECTION 6.8. Subordination May Not Be Impaired.

         No right of any present or future holder of any Senior Indebtedness to
enforce subordination as herein provided shall at any time in any way be
prejudiced or impaired by any act or failure to act on the part of the Company
or by any act or failure to act, in good faith, by any such holder, or by any
noncompliance by the Company with the terms, provisions and covenants of the
Indenture, regardless of any knowledge thereof that any such holder may have or
otherwise be charged with. Without in any way limiting the generality of the
foregoing paragraph, the holders of Senior Indebtedness may, at any time and
from time to time, without the consent of or notice to the Trustee or the
Holders of the Subordinated Debentures, without incurring responsibility to the
Holders of the Subordinated Debentures and without impairing or releasing the
subordination provided in this Article Six or the obligations hereunder of the
Holders of the Subordinated Debentures to the holders of such Senior
Indebtedness, do any one or more the following: (i) change the manner, place or
terms of payment or extend the time of payment of, or renew or alter, such
Senior Indebtedness, or otherwise amend or supplement in any manner such Senior
Indebtedness or any instrument evidencing the same or any agreement under which
such Senior Indebtedness is outstanding; (ii) sell, exchange, release or
otherwise deal with any property pledged, mortgaged or otherwise securing such
Senior Indebtedness; (iii) release any Person liable in any manner for the
collection of such Senior Indebtedness; and (iv) exercise or refrain from
exercising any rights against the Company and any other Person.

<Page>

                                  ARTICLE VII
                                   COVENANTS

         SECTION 7.1. Covenants.

                (a) If Subordinated Debentures are to be distributed to the
holders of the Preferred Securities upon a Dissolution Event, the Company will
use its best efforts to list such Subordinated Debentures on the New York Stock
Exchange or on such other exchange as the Preferred Securities are then listed.

                (b) The Company shall maintain directly or indirectly 100%
ownership of the Common Securities, provided that certain successors that are
permitted pursuant to the Indenture may succeed to the Company's ownership of
the Common Securities;

                (c) The Company will not voluntarily dissolve, wind up or
liquidate the Trust, except

                  (i)      in connection with a distribution of the Subordinated
                           Debentures to the holders of the Preferred Securities
                           in liquidation of the Trust; or

                  (ii)     in connection with certain mergers, consolidations or
                           amalgamations permitted by the Declaration, and

                (d) The Company shall use reasonable efforts, consistent with
the terms and provisions of the Declaration, to cause the Trust to remain
classified as a grantor trust and not as an association taxable as a corporation
for United States federal income tax purposes.

                                  ARTICLE VIII
                         FORM OF SUBORDINATED DEBENTURE

         SECTION 8.1. Form of Subordinated Debenture.

         The Subordinated Debentures and the Trustee's Certificate of
Authentication to be endorsed thereon are to be substantially in the following
forms:

                           (FORM OF FACE OF DEBENTURE)

         [IF THE DEBENTURE IS TO BE A GLOBAL DEBENTURE, INSERT: This
Subordinated Debenture is a Global Debenture within the meaning of the Indenture
hereinafter referred to and is registered in the name of a Depository or a
nominee of a Depository. This Subordinated Debenture is exchangeable for
Subordinated Debentures registered in the name of a person other than the
Depository or its nominee only in the limited circumstances described in the
Indenture, and no transfer of this Subordinated Debenture (other than a transfer
of this Subordinated Debenture as a whole by the Depository to a nominee of the
Depository or by a nominee of the Depository to the Depository or another
nominee of the Depository) may be registered except in limited circumstances.
Unless this Subordinated Debenture is presented by an authorized representative
of The Depository Trust Company (55 Water Street, New York,

<Page>

New York) to the issuer or its agent for registration of transfer, exchange or
payment, and any Subordinated Debenture issued is registered in the name of Cede
& Co. or such other name as requested by an authorized representative of The
Depository Trust Company and any payment hereon is made to Cede & Co., ANY
TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY A PERSON IS
WRONGFUL since the registered owner hereof, Cede & Co., has an interest herein.]

No.___________                                                   $______________
                                                                  CUSIP No.

            8 1/4% JUNIOR SUBORDINATED DEFERRABLE INTEREST DEBENTURE
                              DUE DECEMBER 15, 2031

         NorthWestern Corporation, a Delaware corporation (the "Company", which
term includes any successor corporation under the Indenture hereinafter referred
to), for value received, hereby promises to pay to _________________________, or
registered assigns, the principal sum of ________________________ on December
__, 2031, and to pay interest on said principal sum from December __, 2001, or
from the most recent interest payment date (each such date, an "Interest Payment
Date") to which interest has been paid or duly provided for, quarterly (subject
to deferral as set forth herein) in arrears on March __, June __, September __
and December 15 of each year commencing March __, 2002, at the rate of 8 1/4%
per annum until the principal hereof shall have become due and payable, and on
any overdue principal and premium, if any, and (without duplication and to the
extent that payment of such interest is enforceable under applicable law) on any
overdue installment of interest at the same rate per annum compounded quarterly.
The amount of interest payable on any Interest Payment Date shall be computed on
the basis of a 360-day year of twelve 30-day months. In the event that any date
on which interest is payable on this Subordinated Debenture is not a Business
Day, then payment of interest payable on such date will be made on the next
succeeding day that is a Business Day (and without any interest or other payment
in respect of any such delay), except that, if such Business Day is in the next
succeeding calendar year, such payment shall be made on the immediately
preceding Business Day, in each case with the same force and effect as if made
on such date. The interest installment so payable, and punctually paid or duly
provided for, on any Interest Payment Date will, as provided in the Indenture,
be paid to the person in whose name this Subordinated Debenture (or one or more
Predecessor Securities, as defined in said Indenture) is registered at the close
of business on the Regular Record Date for such interest installment, which, if
this Subordinated Debenture is held by the Property Trustee or is a Global
Debenture, shall be the close of business on the Business Day next preceding
such Interest Payment Date or, if the Preferred Securities are no longer in
book-entry only form or this Subordinated Debenture is not a Global Debenture,
shall be 15 Business Days before the relevant Interest Payment Date; provided
that interest paid at maturity shall be paid to the Person to whom principal is
paid. Any such interest installment not punctually paid or duly provided for
shall forthwith cease to be payable to the registered Holders on such Regular
Record Date and may be paid to the Person in whose name this Subordinated
Debenture (or one or more Predecessor Securities) is registered at the close of
business on a special record date to be fixed

<Page>

by the Trustee for the payment of such defaulted interest, notice whereof shall
be given to the registered Holders of the Subordinated Debentures not less than
10 days prior to such special record date, or may be paid at any time in any
other lawful manner not inconsistent with the requirements of any securities
exchange on which the Subordinated Debentures may be listed, and upon such
notice as may be required by such exchange, all as more fully provided in the
Indenture. The principal of (and premium, if any) and interest on this
Subordinated Debenture shall be payable at the office or agency of the Trustee
maintained for that purpose in any coin or currency of the United States of
America that at the time of payment is legal tender for payment of public and
private debts; PROVIDED, HOWEVER, that payment of interest may be made at the
option of the Company by check mailed to the registered Holder at such address
as shall appear in the Security Register. Notwithstanding the foregoing, so long
as the Holder of this Subordinated Debenture is the Property Trustee, the
payment of the principal of (and premium, if any) and interest on this
Subordinated Debenture will be made at such place and to such account as may be
designated by the Property Trustee.

         The indebtedness evidenced by this Subordinated Debenture is, to the
extent provided in the Indenture, subordinate and junior in right of payment to
the prior payment in full of all Senior Indebtedness, and this Subordinated
Debenture is issued subject to the provisions of the Indenture with respect
thereto. Each Holder of this Subordinated Debenture, by accepting the same, (a)
agrees to and shall be bound by such provisions, (b) authorizes and directs the
Trustee on his or her behalf to take such action as may be necessary or
appropriate to acknowledge or effectuate the subordination so provided and (c)
appoints the Trustee his or her attorney-in-fact for any and all such purposes.
Each Holder hereof, by his or her acceptance hereof, hereby waives all notice of
the acceptance of the subordination provisions contained herein and in the
Indenture by each holder of Senior Indebtedness, whether now outstanding or
hereafter incurred, and waives reliance by each such holder upon said
provisions.

         Unless the Certificate of Authentication hereon has been executed by
the Trustee referred to on the reverse side hereof, this Subordinated Debenture
shall not be entitled to any benefit under the Indenture or be valid or
obligatory for any purpose.

         The provisions of this Subordinated Debenture are continued on the
reverse side hereof, and such continued provisions shall for all purposes have
the same effect as though fully set forth at this place.

<Page>

         IN WITNESS WHEREOF, the Company has caused this instrument to be
executed.

Dated:   December ____, 2001
                                        NORTHWESTERN CORPORATION

                                        By: ___________________________________
                                            Name:
                                            Title:
Attest:

By: __________________________
    Assistant Secretary

                          CERTIFICATE OF AUTHENTICATION

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

                                            JPMorgan Chase Bank, as Trustee

                                            By: __________________________
                                                Authorized Officer

<Page>

                         (FORM OF REVERSE OF DEBENTURE)

         This Subordinated Debenture is one of a duly authorized series of
Securities of the Company (herein sometimes referred to as the "Subordinated
Debentures"), all issued under and pursuant to an Indenture dated as of August
1, 1995, duly executed and delivered between the Company and JPMorgan Chase Bank
(as successor to The Chase Manhattan Bank), as Trustee (the "Trustee"), as
supplemented by the First Supplemental Indenture thereto dated as of August 1,
1995 and as further supplemented by the Second Supplemental Indenture thereto
dated as of November 15, 1998 and as further supplemented by the Third
Supplemental Indenture thereto dated as of December __, 2001, between the
Company and the Trustee (such Indenture as so supplemented, the "Indenture"), to
which Indenture and all indentures supplemental thereto reference is hereby made
for a description of the rights, limitations of rights, obligations, duties and
immunities thereunder of the Trustee, the Company and the Holders of the
Subordinated Debentures. By the terms of the Indenture, the Securities are
issuable in series that may vary as to amount, date of maturity, rate of
interest and in other respects as provided in the Indenture. This series of
Securities is limited in aggregate principal amount to $103,092,800; PROVIDED,
HOWEVER, if the Overallotment Option is exercised, the aggregate principal
amount may be increased to up to $118,556,725.

         The Company shall have the right to redeem this Subordinated Debenture
at the option of the Company, without premium or penalty, (i) in whole or in
part at any time on or after December __, 2006 and (ii) in whole (but not in
part) at any time before December __, 2006 in certain circumstances upon the
occurrence of a Tax Event or an Investment Company Event, in each case at a
redemption price equal to 100% of the principal amount plus any accrued but
unpaid interest hereon to the date of such redemption (the "Redemption Price").
Any redemption pursuant to this paragraph will be made upon not less than 30 nor
more than 60 days' notice, at the Redemption Price. The Company may not redeem
fewer than all of the Subordinated Debentures unless all accrued and unpaid
interest has been paid on all Subordinated Debentures for all quarterly interest
payment periods terminating on or prior to the date of redemption. If a partial
redemption of the Subordinated Debentures would result in the delisting of the
Preferred Securities issued by the Trust from any national securities exchange
or other organization on which the Preferred Securities are then listed, the
Company shall not be permitted to effect such partial redemption and may only
redeem the Subordinated Debentures in whole. If the Subordinated Debentures are
only partially redeemed by the Company, the particular Subordinated Debentures
to be redeemed will be selected on a pro rata basis by such method as the
Trustee shall deem fair and appropriate or, if the Subordinated Debentures are
registered as a Global Debenture, in accordance with the Depository's customary
procedures.

         In the event of redemption of this Subordinated Debenture in part only,
a new Subordinated Debenture or Debentures for the unredeemed portion hereof
will be issued in the name of the Holder hereof upon the cancellation hereof.

         In case an Event of Default, as defined in the Indenture, shall have
occurred and be continuing, the principal of all of the Subordinated Debentures
may be declared, and upon such declaration shall become, due and payable, in the
manner, with the effect and subject to the conditions provided in the Indenture.

                                      -2-

<Page>

         The Indenture contains provisions permitting the Company and the
Trustee, with the consent of the Holders of not less than a majority in
aggregate principal amount of the Subordinated Debentures and all other series
of Securities affected at the time Outstanding, as defined in the Indenture, to
execute supplemental indentures for the purpose of adding any provisions to or
changing in any manner or eliminating any of the provisions of the Indenture or
of any supplemental indenture or of modifying in any manner the rights of the
Holders of the Subordinated Debentures; PROVIDED, HOWEVER, that no such
supplemental indenture may, without the consent of the Holder of each
outstanding Subordinated Debenture, among other things, (i) change the stated
maturity of the principal of, or any installment of interest on, any
Subordinated Debenture, (ii) reduce the principal amount of, or the rate of
interest on or any Additional Sums payable in respect of, or any premium payable
upon the redemption of, the Subordinated Debentures, or change the redemption
provisions of the Subordinated Debentures, (iii) impair the right to institute
suit for the enforcement of any such payment on or after the stated maturity of
or any redemption date for the Subordinated Debentures or (iv) reduce the
above-stated percentage of principal amount of Subordinated Debentures, the
Holders of which are required to modify or amend the Indenture, to consent to
any waiver thereunder or to approve any supplemental indenture. The Indenture
also contains provisions permitting the Holders of a majority in aggregate
principal amount of the Subordinated Debentures at the time outstanding affected
thereby, on behalf of all of the Holders of the Subordinated Debentures, to
waive any past default in the performance of any of the covenants contained in
the Indenture, or established pursuant to the Indenture with respect to the
Subordinated Debentures, and its consequences, except a default in the payment
of the principal of or interest on any of the Subordinated Debentures (unless
cured as provided in the Indenture) or in respect of a covenant or provision
that cannot be modified or amended without the consent of the Holders of each
Subordinated Debenture then outstanding. Any such consent or waiver by the
registered Holder of this Subordinated Debenture (unless revoked as provided in
the Indenture) shall be conclusive and binding upon such Holder and upon all
future Holders and owners of this Subordinated Debenture and of any Subordinated
Debenture issued in exchange herefor or in place hereof (whether by registration
of transfer or otherwise), irrespective of whether or not any notation of such
consent or waiver is made upon this Subordinated Debenture.

         No reference herein to the Indenture and no provision of this
Subordinated Debenture or of the Indenture shall alter or impair the obligation
of the Company, which is absolute and unconditional, to pay the principal of and
premium, if any, and interest on this Subordinated Debenture at the time and
place and at the rate and in the money herein prescribed.

         So long as no Event of Default has occurred and is continuing, the
Company shall have the right at any time during the term of this Subordinated
Debenture from time to time to extend the interest payment period hereof to up
to 20 consecutive quarters, but not beyond the Maturity Date of this
Subordinated Debenture (an "Extended Interest Payment Period"), at the end of
which period the Company shall pay all interest then accrued and unpaid
(together with interest thereon at the rate specified herein to the extent that
payment of such interest is enforceable under applicable law).

         Before the termination of any such Extended Interest Payment Period,
the Company may further extend such Extended Interest Payment Period, provided
that such Extended Interest Payment Period together with all such previous and
further extensions thereof shall not exceed

                                      -3-

<Page>

20 consecutive quarters or extend beyond the Maturity Date. At the termination
of any such Extended Interest Payment Period and upon the payment of all accrued
and unpaid interest and any additional amounts then due, the Company may
commence a new Extended Interest Payment Period.

         As provided in the Indenture and subject to certain limitations therein
set forth, this Subordinated Debenture is transferable by the registered Holder
hereof on the Security Register of the Company, upon surrender of this
Subordinated Debenture for registration of transfer at the office or agency of
the Company in the City and State of New York accompanied by a written
instrument or instruments of transfer in form satisfactory to the Company or the
Trustee duly executed by the registered Holder hereof or his attorney duly
authorized in writing, and thereupon one or more new Subordinated Debentures of
authorized denominations and for the same aggregate principal amount will be
issued to the designated transferee or transferees. No service charge will be
made for any such transfer, but the Company may require payment of a sum
sufficient to cover any tax or other governmental charge payable in relation
thereto.

         Prior to due presentment for registration of transfer of this
Subordinated Debenture, the Company, the Trustee, any paying agent and any
Security Registrar may deem and treat the registered holder hereof as the
absolute owner hereof (whether or not this Subordinated Debenture shall be
overdue and notwithstanding any notice of ownership or writing hereon made by
anyone other than the Security Registrar) for the purpose of receiving payment
of or on account of the principal hereof and premium, if any, and interest due
hereon and for all other purposes, and neither the Company nor the Trustee nor
any paying agent nor any Security Registrar shall be affected by any notice to
the contrary.

         No recourse shall be had for the payment of the principal of or the
interest on this Subordinated Debenture, or for any claim based hereon, or
otherwise in respect hereof, or based on or in respect of the Indenture, against
any incorporator, stockholder, officer or director, past, present or future, as
such, of the Company or of any predecessor or successor corporation, whether by
virtue of any constitution, statute or rule of law, or by the enforcement of any
assessment or penalty or otherwise, all such liability being, by the acceptance
hereof and as part of the consideration for the issuance hereof, expressly
waived and released.

         The Subordinated Debentures of this series are issuable only in
registered form without coupons in denominations of $25 and any integral
multiple thereof. As provided in the Indenture and subject to certain
limitations herein and therein set forth, Subordinated Debentures of this series
so issued are exchangeable for a like aggregate principal amount of Subordinated
Debentures of this series of a different authorized denomination, as requested
by the Holder surrendering the same.

         All terms used in this Subordinated Debenture that are defined in the
Indenture shall have the meanings assigned to them in the Indenture.

                                      -4-

<Page>

                                   ARTICLE IX
                    ORIGINAL ISSUE OF SUBORDINATED DEBENTURES

         SECTION 9.1. Original Issue of Subordinated Debentures.

         Subordinated Debentures may, upon execution of this Third Supplemental
Indenture, be executed by the Company and delivered to the Trustee for
authentication, and the Trustee shall thereupon authenticate and deliver said
Subordinated Debentures to or upon receipt of a Company Order, without any
further action by the Company.

                                   ARTICLE X
                    RIGHTS OF HOLDERS OF PREFERRED SECURITIES

         SECTION 10.1. Preferred Security Holders' Rights.

         Notwithstanding Section 507 of the Indenture, if the Property Trustee
fails to enforce its rights under the Declaration or the Subordinated
Debentures, any holder of Preferred Securities may institute a legal proceeding
against the Company to enforce the Property Trustee's rights under the
Declaration or the Subordinated Debentures without first instituting any legal
proceeding against the Property Trustee or any other Person or entity.

         SECTION 10.2. Direct Action.

         Notwithstanding any other provision of the Indenture, for as long as
any Preferred Securities remain outstanding, to the fullest extent permitted by
law, if an Event of Default has occurred and is continuing and such event is
attributable to the failure of the Company to pay interest or principal on the
Subordinated Debentures on the date such interest or principal is due and
payable, any holder of Preferred Securities shall have the right to institute a
proceeding directly against the Company for enforcement of payment to such
holder of the principal of or interest (including any Compounded Interest or
Additional Sums) on Subordinated Debentures having an aggregate principal amount
equal to the aggregate liquidation amount of such holder's Preferred Securities
(a "Direct Action"). The Company may not amend this Subordinated Indenture to
remove the right to bring a Direct Action without the prior written consent of
the holders of all the Preferred Securities then outstanding.

         SECTION 10.3. Payments Pursuant to Direct Actions.

         The Company shall have the right to set-off against its obligations to
the Trust, as Holder of the Subordinated Debentures, any payment made to a
holder of Preferred Securities in connection with a Direct Action.

                                      -5-

<Page>

                                   ARTICLE XI
                                  MISCELLANEOUS

         SECTION 11.1. Ratification of Indenture.

         The Indenture, as heretofore supplemented and as further supplemented
by this Third Supplemental Indenture, is in all respects ratified and confirmed,
and this Third Supplemental Indenture shall be deemed part of the Indenture in
the manner and to the extent herein and therein provided.

         SECTION 11.2. Trustee Not Responsible for Recitals.

         The recitals herein contained are made by the Company and not by the
Trustee, and the Trustee assumes no responsibility for the correctness thereof.
The Trustee makes no representation as to the validity or sufficiency of this
Third Supplemental Indenture.

         SECTION 11.3. Governing Law.

         This Third Supplemental Indenture and each Subordinated Debenture shall
be deemed to be a contract made under the internal laws of the State of New York
and for all purposes shall be construed in accordance with the laws of said
State.

         SECTION 11.4. Separability.

         In case any one or more of the provisions contained in this Third
Supplemental Indenture or in the Subordinated Debentures shall for any reason be
held to be invalid, illegal or unenforceable in any respect, such invalidity,
illegality or unenforceability shall not affect any other provisions of this
Third Supplemental Indenture or of the Subordinated Debentures, but this Third
Supplemental Indenture and the Subordinated Debentures shall be construed as if
such invalid or illegal or unenforceable provision had never been contained
herein or therein.

         SECTION 11.5. Counterparts.

         This Third Supplemental Indenture may be executed in any number of
counterparts each of which shall be an original; but such counterparts shall
together constitute but one and the same instrument.

         SECTION 11.6. Overallotment Option.

         This Third Supplemental Indenture shall permit the issuance from time
to time, subject to the terms of the Overallotment Option, of additional
Subordinated Debentures of this series in accordance with the procedures
established in Section 303 of the Indenture.

                                      -6-

<Page>

         IN WITNESS WHEREOF, the parties hereto have caused this Third
Supplemental Indenture to be duly executed, and their respective corporate seals
to be hereunto affixed and attested, on the date or dates indicated in the
acknowledgments and as of the day and year first above written.

                                  NORTHWESTERN CORPORATION

                                  By: /s/ Kipp D. Orme
                                      ------------------------------------------
                                  Name:  Kipp D. Orme
                                  Title: Vice President--Finance and CFO

Attest: /s/ Alan D. Dietrich
        --------------------------------
Name:   Alan D. Dietrich
Title:  Corporate Secretary

                                  JPMORGAN CHASE BANK

                                  By: /s/ R.J. Halleran
                                      ------------------------------------------
                                  Name: R.J. Halleran
                                  Title: Assistant Vice President

Attest: /s/ Natalie B. Pesce
        --------------------------------
Name:   Natalie B. Pesce
Title:  Asst. Corporate Secretary and
        Trust Officer

<Page>

STATE OF SOUTH DAKOTA      )
                           )  SS
COUNTY OF MINNEHAHA        )

         On the day of December 21, 2001, before me personally Kipp D. Orme
and came to be known, who, being by me duly sworn, did depose and say that he
is the Vice President-Finance and Chief Financial Officer of NorthWestern
Corporation, one of the corporations described in and which executed the
above instrument; that he knows the corporate seal of said corporation; that
the seal affixed to the said instrument is such corporation seal; that it was
so affixed by authority of the Board of Directors of said corporation, and
that he signed his name thereto by like authority.

         IN WITNESS WHEREOF, I have hereunto set my hand and affixed my seal of
office this 21st day of December, 2001.

(Notarial Seal)                            /s/ Alan Dietrich
                                           -------------------------------------
                                                     Alan Dietrich
                                           NOTARY PUBLIC, MINNEHAHA COUNTY, S.D.
                                            My Commission Expires March 30, 2009

STATE OF NEW YORK          )
                           )  SS
COUNTY OF NEW YORK         )

         On the day of December 21, 2001, before me personally Ronald J.
Halleran came to be known, who, being by me duly sworn, did depose and say
that he is the Assistant Vice President of JPMorgan Chase Bank, one of the
corporations described in and which executed the above instrument; that he
knows the corporate seal of said corporation; that the seal affixed to the
said instrument is such corporation seal; that it was so affixed by authority
of the Board of Directors of said corporation, and that he signed his name
thereto by like authority.

         IN WITNESS WHEREOF, I have hereunto set my hand and affixed my seal of
office this 21st day of December, 2001.

(Notarial Seal)                            /s/ Emily Fayan
                                           -------------------------------------
                                           NOTARY PUBLIC, KINGS COUNTY, N.Y.
                                           My Commission Expires 2005<Page>

                                                                    Exhibit 4.7

                    PREFERRED SECURITIES GUARANTEE AGREEMENT

<Page>

                        NORTHWESTERN CAPITAL FINANCING II

                              CROSS-REFERENCE TABLE
                           FOR THE GUARANTEE AGREEMENT

<Table>
<Caption>
SECTION OF                                                                                      SECTION OF
TRUST INDENTURE ACT                                                                              GUARANTEE
OF 1939, AS AMENDED                                                                              AGREEMENT

<S>                                                                                     <C>
Section   310(a)....................................................................................4.1(a)
          310(b)...............................................................................4.1(c), 2.8
          310(c)............................................................................Not Applicable
Section   311(a)....................................................................................2.2(b)
          311(b)....................................................................................2.2(b)
          311(c)............................................................................Not Applicable
Section   312(a)....................................................................................2.2(a)
          312(b)....................................................................................2.2(b)
Section   313..........................................................................................2.3
Section   314(a).......................................................................................2.4
          314(b)............................................................................Not Applicable
          314(c).......................................................................................2.5
          314(d)............................................................................Not Applicable
          314(e).............................................................................2.4, 2.5, 3.2
          314(f)..................................................................................2.1, 3.2
Section   315(a)....................................................................................3.1(d)
          315(b).......................................................................................2.6
          315(c).......................................................................................3.1
          315(d)....................................................................................3.1(d)
Section   316(a)...............................................................................5.4(a), 2.6
          316(b).......................................................................................5.3
          316(c).......................................................................................2.2
Section   317(a)............................................................................Not Applicable
          317(b)............................................................................Not Applicable
Section   318(a)....................................................................................2.1(b)
          318(b).......................................................................................2.1
          318(c)....................................................................................2.1(a)
</Table>
----------
Note: This table of contents shall not, for any purpose, be deemed to be a part
of the Guarantee Agreement.

                                      -i-

<Page>

                                          TABLE OF CONTENTS

<Table>
<Caption>
                                                                                               PAGE
                                              ARTICLE I                                        ----
                                     Definitions and Interpretation
<S>                                                                                          <C>
SECTION 1.1.   Definitions and Interpretation....................................................1
               Affiliate.........................................................................2
               Common Securities.................................................................2
               Common Securities Guarantee Agreement.............................................2
               Covered Person....................................................................2
               Event of Default..................................................................2
               Guarantee Payments................................................................3
               Holder............................................................................3
               Indemnified Person................................................................3
               Indenture.........................................................................3
               Majority in liquidation amount of the Securities..................................3
               Officers' Certificate.............................................................3
               Person............................................................................4
               Preferred Guarantee Trustee.......................................................4
               Responsible Officer...............................................................4
               Successor Preferred Guarantee Trustee.............................................4
               Trust Indenture Act...............................................................4

                                              ARTICLE II
                                          Trust Indenture Act

SECTION 2.1.   Trust Indenture Act; Application..................................................4
SECTION 2.2.   Lists of Holders of Securities....................................................5
SECTION 2.3.   Reports by the Preferred Guarantee Trustee........................................5
SECTION 2.4.   Periodic Reports to Preferred Guarantee Trustee...................................5
SECTION 2.5.   Evidence of Compliance with Conditions Precedent..................................5
SECTION 2.6.   Events of Default; Waiver.........................................................6
SECTION 2.7.   Conflicting Interests.............................................................6

                                             ARTICLE III
                        Powers, Duties and Rights of Preferred Guarantee Trustee

SECTION 3.1.   Powers and Duties of the Preferred Guarantee Trustee..............................6
SECTION 3.2.   Certain Rights of Preferred Guarantee Trustee.....................................8
SECTION 3.3.   Not Responsible for Recitals or Issuance of Guarantee............................10

                                             ARTICLE IV
                                    Preferred Guarantee Trustee

SECTION 4.1.   Preferred Guarantee Trustee; Eligibility.........................................11
SECTION 4.2.   Appointment, Removal and Resignation of Preferred Guarantee Trustees.............12
</Table>

                                       -i-

<Page>

                                         TABLE OF CONTENTS
                                            (Continued)
<Table>
<Caption>
                                                                                               PAGE
                                             ARTICLE V                                         ----
                                             Guarantee
<S>                                                                                         <C>
SECTION 5.1.   Guarantee........................................................................12
SECTION 5.2.   Waiver of Notice and Demand......................................................13
SECTION 5.3.   Obligations Not Affected.........................................................13
SECTION 5.4.   Rights of Holders................................................................14
SECTION 5.5.   Guarantee of Payment.............................................................14
SECTION 5.6.   Subrogation......................................................................14
SECTION 5.7.   Independent Obligations..........................................................15

                                             ARTICLE VI
                             Limitation of Transactions; Subordination

SECTION 6.1.   Limitation of Transactions.......................................................15
SECTION 6.2.   Ranking..........................................................................15

                                             ARTICLE VII
                                             Termination

SECTION 7.1.   Termination......................................................................16

                                             ARTICLE VIII
                                            Indemnification

SECTION 8.1.   Exculpation......................................................................17
SECTION 8.2.   Indemnification..................................................................17

                                             ARTICLE IX
                                            Miscellaneous

SECTION 9.1.   Successors and Assigns...........................................................18
SECTION 9.2.   Amendments.......................................................................18
SECTION 9.3.   Notices..........................................................................18
SECTION 9.4.   Benefit..........................................................................19
SECTION 9.5.   Governing Law....................................................................19
TESTIMONIUM.....................................................................................20
SIGNATURES......................................................................................20
</Table>

----------
Note: This table of contents shall not, for any purpose, be deemed to be a part
of the Guarantee Agreement.

                                      -ii-

<Page>

                    PREFERRED SECURITIES GUARANTEE AGREEMENT

                          DATED AS OF DECEMBER 21, 2001

This GUARANTEE AGREEMENT ("GUARANTEE AGREEMENT"), dated as of December 21, 2001,
is executed and delivered by NorthWestern Corporation, a Delaware corporation
(the "GUARANTOR"), and Wilmington Trust Company, a Delaware banking corporation,
not in its individual capacity but solely as trustee for the benefit of the
Holders (as defined herein) from time to time of the Preferred Securities (as
defined herein) of Northwestern Capital Financing II, a Delaware statutory
business trust (the "ISSUER").

WHEREAS, pursuant to an Amended and Restated Declaration of Trust (the
"DECLARATION"), dated as of December 21, 2001, among the trustees of the Issuer
named therein, the Guarantor, as sponsor of the Issuer, and the holders from
time to time of undivided beneficial interests in the assets of the Issuer, the
Issuer is issuing on the date hereof $100,000,000 aggregate stated liquidation
amount of Preferred Securities, and if the Overallotment Option (as defined in
the Declaration) is exercised, an aggregate stated liquidation amount of up to
$115,000,000, designated the 8 1/4% Trust Preferred Securities (the "PREFERRED
SECURITIES");

WHEREAS, as incentive for the Holders to purchase the Preferred Securities, the
Guarantor desires irrevocably and unconditionally to agree, to the extent set
forth in this Guarantee Agreement, to pay to the Holders of the Preferred
Securities the Guarantee Payments (as defined herein) and to make certain other
payments on the terms and conditions set forth herein;

NOW, THEREFORE, in consideration of the purchase by each Holder of Preferred
Securities, which purchase the Guarantor hereby agrees shall benefit the
Guarantor, the Guarantor executes and delivers this Guarantee Agreement for the
benefit of the Holders.

                                    ARTICLE I
                         DEFINITIONS AND INTERPRETATION

SECTION 1.1.   DEFINITIONS AND INTERPRETATION.

In this Guarantee Agreement, unless the context otherwise requires:

     (a)  Capitalized terms used in this Guarantee Agreement but not defined in
          the preamble above or otherwise in this Guarantee Agreement have the
          respective meanings assigned to them in the Declaration as in effect
          on the date hereof;
<Page>

     (b)  a term defined anywhere in this Guarantee Agreement has the same
          meaning throughout;

     (c)  all references to "the Guarantee Agreement" or "this Guarantee
          Agreement" are to this Guarantee Agreement as modified, supplemented
          or amended from time to time;

     (d)  all references in this Guarantee Agreement to Articles and Sections
          are to Articles and Sections of this Guarantee Agreement unless
          otherwise specified;

     (e)  a term defined in the Trust Indenture Act has the same meaning when
          used in this Guarantee Agreement unless otherwise defined in this
          Guarantee Agreement or unless the context otherwise requires; and

     (f)  a reference to the singular includes the plural and vice versa.

"AFFILIATE" has the same meaning as given to that term in Rule 405 promulgated
under the Securities Act of 1933, as amended, or any successor rule thereunder.

"COMMON SECURITIES" means the securities representing common undivided
beneficial interests in the assets of the Issuer.

"COMMON SECURITIES GUARANTEE AGREEMENT" means the guarantee agreement dated the
date hereof executed by the Guarantor for the benefit of the holders from time
to time of the Common Securities.

"COVERED PERSON" means any Holder or beneficial owner of Preferred Securities.

"EVENT OF DEFAULT" means a default by the Guarantor on any of its payment or
other obligations under this Guarantee Agreement.

"GUARANTEE PAYMENTS" means the following payments or distributions, without
duplication, with respect to the Preferred Securities, to the extent not paid
or made by the Issuer: (i) any accumulated and unpaid Distributions (as
defined in the Declaration) that are required to be paid on such Preferred
Securities to the extent the Issuer has funds legally available therefor,
(ii) the redemption price, including all accumulated and unpaid Distributions
to the date of redemption (the "REDEMPTION PRICE"), to the extent the Issuer
has funds legally available therefor, with respect to any Preferred
Securities called for redemption by the Issuer, and (iii) upon a voluntary or
involuntary dissolution, winding-up or termination of the Issuer (other than
in connection with the distribution of Debentures to the Holders in exchange
for Preferred Securities as provided in the Declaration or a redemption of
all the Preferred Securities), the lesser of (a) the aggregate of the
liquidation amount and all accumulated and unpaid Distributions on the
Preferred Securities to the date of payment to the extent the Issuer has
funds legally available

                                       2

<Page>

therefor, and (b) the amount of assets of the Issuer remaining available for
distribution to Holders in liquidation of the Issuer (in either case, the
"LIQUIDATION DISTRIBUTION"). If an event of default under the Indenture has
occurred and is continuing, the rights of holders of the Common Securities to
receive payments under the Common Securities Guarantee Agreement are
subordinated to the rights of Holders of Preferred Securities to receive
Guarantee Payments under this Guarantee Agreement.

"HOLDER" shall mean any holder, as registered on the books and records of the
Issuer, of any Preferred Securities; provided, however, that, in determining
whether the Holders of the requisite percentage of Preferred Securities have
given any request, notice, consent or waiver hereunder, "Holder" shall not
include the Guarantor or any Affiliate of the Guarantor.

"INDEMNIFIED PERSON" means the Preferred Guarantee Trustee, any Affiliate of the
Preferred Guarantee Trustee, or any officers, directors, shareholders, members,
partners, employees, representatives or agents of the Preferred Guarantee
Trustee.

"INDENTURE" means the Indenture dated as of August 1, 1995, as supplemented,
between the Guarantor (the "DEBENTURE ISSUER") and JPMorgan Chase Bank (as
successor to The Chase Manhattan Bank), as trustee, and any indenture
supplemental thereto pursuant to which certain subordinated debt securities of
the Debenture Issuer are to be issued to the Property Trustee of the Issuer.

"MAJORITY IN LIQUIDATION AMOUNT OF THE SECURITIES" means, except as provided by
the Trust Indenture Act, a vote by the Holders of Preferred Securities, voting
separately as a class, of more than 50% of the liquidation amount (including the
stated amount that would be paid on redemption, liquidation or otherwise, plus
accumulated and unpaid Distributions to the date upon which the voting
percentages are determined) of all Preferred Securities.

"OFFICERS' CERTIFICATE" means, with respect to any Person, a certificate signed
by two Authorized Officers of such Person. Any Officers' Certificate delivered
with respect to compliance with a condition or covenant provided for in this
Guarantee Agreement shall include:

     (a)  a statement that each officer signing the Officers' Certificate has
          read the covenant or condition and the definition relating thereto;

     (b)  a brief statement of the nature and scope of the examination or
          investigation undertaken by each officer in rendering the Officers'
          Certificate;

     (c)  a statement that each such officer has made such examination or
          investigation as, in such officer's opinion, is necessary to enable
          such

                                       3

<Page>

          officer to express an informed opinion as to whether or not such
          covenant or condition has been complied with; and

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

"PERSON" means a legal person, including any individual, corporation, estate,
partnership, joint venture, association, joint stock company, limited liability
company, trust, unincorporated association, or government or any agency or
political subdivision thereof, or any other entity of whatever nature.

"PREFERRED GUARANTEE TRUSTEE" means Wilmington Trust Company, in its capacity as
trustee hereunder and not in its individual capacity, until a Successor
Preferred Guarantee Trustee has been appointed and has accepted such appointment
pursuant to the terms of this Guarantee Agreement and thereafter means each such
Successor Preferred Guarantee Trustee.

"RESPONSIBLE OFFICER" means, with respect to the Preferred Guarantee Trustee,
any vice-president, any assistant vice-president, the secretary, any assistant
secretary, the treasurer, any assistant treasurer, any trust officer or
assistant trust officer or any other officer of the Corporate Trust Department
of the Preferred Guarantee 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 that officer's knowledge of and familiarity with
the particular subject.

"SUCCESSOR PREFERRED GUARANTEE TRUSTEE" means a successor Preferred Guarantee
Trustee possessing the qualifications to act as Preferred Guarantee Trustee
under Section 4.1.

"TRUST INDENTURE ACT" means the Trust Indenture Act of 1939, as amended.

                                   ARTICLE II
                               TRUST INDENTURE ACT

SECTION 2.1.   TRUST INDENTURE ACT; APPLICATION.

     (a)  This Guarantee Agreement is subject to the provisions of the Trust
          Indenture Act that are required to be part of this Guarantee Agreement
          and shall, to the extent applicable, be governed by such provisions;
          and

                                       4

<Page>

     (b)  if and to the extent that any provision of this Guarantee Agreement
          limits, qualifies or conflicts with the duties imposed by Section 310
          to 317, inclusive, of the Trust Indenture Act, such imposed duties
          shall control.

SECTION 2.2.   LISTS OF HOLDERS OF SECURITIES.

     (a)  The Guarantor shall provide the Preferred Guarantee Trustee with a
          list, in such form as the Preferred Guarantee Trustee may reasonably
          require, of the name and addresses of the Holders of the Preferred
          Securities as of such date, (i) within 14 days after January 1 and
          June 30 of each year, and (ii) at any other time within 30 days of
          receipt by the Guarantor of a written request for a list of holders as
          of a date no more than 14 days before such list of holders is given to
          the Preferred Guarantee Trustee, provided that the Guarantor shall not
          be obligated to provide such list of holders at any time the list of
          holders does not differ from the most recent list of holders given to
          the Preferred Guarantee Trustee by the Guarantor. The Preferred
          Guarantee Trustee may destroy any list of holders previously given to
          it on receipt of a new list of holders.

     (b)  The Preferred Guarantee Trustee shall comply with Trust Indenture Act.

SECTION 2.3.   REPORTS BY THE PREFERRED GUARANTEE TRUSTEE. Within 60 days
after May 15 of each year, the Preferred Guarantee Trustee shall provide to the
Holders of the Preferred Securities such reports as are required by Section 313
of the Trust Indenture Act, if any, in the form and in the manner provided by
Section 313 of the Trust Indenture Act. The Preferred Guarantee Trustee shall
also comply with the requirements of Section 313(d) of the Trust Indenture Act.

SECTION 2.4.   PERIODIC REPORTS TO PREFERRED GUARANTEE TRUSTEE. The Guarantor
shall provide to the Preferred Guarantee Trustee such documents, reports and
information as required by Section 314 (if any) and the compliance certificate
required by Section 314 of the Trust Indenture Act in the form, in the manner
and at the times required by Section 314 of the Trust Indenture Act.

SECTION 2.5.   EVIDENCE OF COMPLIANCE WITH CONDITIONS PRECEDENT. The
Guarantor shall provide to the Preferred Guarantee Trustee such evidence of
compliance with any conditions precedent, if any, provided for in this Guarantee
Agreement that relate to any of the matters set forth in Section 314(c) of the
Trust Indenture Act. Any certificate or opinion required to be given by an
officer pursuant to Section 314(c)(1) may be given in the form of an Officers'
Certificate.

SECTION 2.6.   EVENTS OF DEFAULT; WAIVER. The Holders of a Majority in
liquidation amount of Preferred Securities may, by vote, on behalf of the
Holders of all of the Preferred Securities, waive any past Event of Default and
its consequences. Upon such waiver, any such Event of Default shall cease to
exist, and any Event of Default arising

                                       5
<Page>

therefrom shall be deemed to have been cured, for every purpose of this
Guarantee Agreement, but no such waiver shall extend to any subsequent or other
default or Event of Default or impair any right consequent thereon.

SECTION 2.7.   EVENT OF DEFAULT; NOTICE.

     (a)  The Preferred Guarantee Trustee shall, within 90 days after the
          occurrence of an Event of Default, transmit by mail, first class
          postage prepaid, to the Holders of the Preferred Securities, notices
          of all Events of Default known to the Preferred Guarantee Trustee,
          unless such defaults have been cured before the giving of such notice,
          provided that the Preferred Guarantee 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 and/or
          Responsible Officers of the Preferred Guarantee Trustee in good faith
          determines that the withholding of such notice is in the interests of
          the Holders of the Preferred Securities.

     (b)  The Preferred Guarantee Trustee shall not be deemed to have knowledge
          of any Event of Default unless the Preferred Guarantee Trustee shall
          have received written notice, or a Responsible Officer charged with
          the administration of the Declaration shall have obtained written
          notice, of such Event of Default.

SECTION 2.8.   CONFLICTING INTERESTS.

The Declaration shall be deemed to be specifically described in this Guarantee
Agreement for the purposes of clause (i) of the first proviso contained in
Section 310(b) of the Trust Indenture Act.

                                  ARTICLE III
                          POWERS, DUTIES AND RIGHTS OF
                           PREFERRED GUARANTEE TRUSTEE

SECTION 3.1.   POWERS AND DUTIES OF THE PREFERRED GUARANTEE TRUSTEE.

     (a)  This Guarantee Agreement shall be held by the Preferred Guarantee
          Trustee for the benefit of the Holders of the Preferred Securities,
          and the Preferred Guarantee Trustee shall not transfer this Guarantee
          Agreement to any Person except a Holder of Preferred Securities
          exercising his or her rights pursuant to Section 5.4(b) or to a
          Successor Preferred Guarantee Trustee on acceptance by such Successor
          Preferred Guarantee Trustee of its appointment to act as Successor
          Preferred Guarantee Trustee. The right, title and interest of the
          Preferred Guarantee Trustee shall

                                       6
<Page>

          automatically vest in any Successor Preferred Guarantee Trustee, and
          such vesting and cessation of title shall be effective whether or not
          conveyancing documents have been executed and delivered pursuant to
          the appointment of such Successor Preferred Guarantee Trustee.

     (b)  If an Event of Default has occurred and is continuing, the Preferred
          Guarantee Trustee shall enforce this Guarantee Agreement for the
          benefit of the Holders of the Preferred Securities.

     (c)  The Preferred Guarantee Trustee, before the occurrence of any Event of
          Default and after the curing of all Events of Default that may have
          occurred, shall undertake to perform only such duties as are
          specifically set forth in this Guarantee Agreement, and no implied
          covenants shall be read into this Guarantee Agreement against the
          Preferred Guarantee Trustee. In case an Event of Default has occurred
          (that has not been cured or waived pursuant to Section 2.6), the
          Preferred Guarantee Trustee shall exercise such of the rights and
          powers vested in it by this Guarantee Agreement, and use the same
          degree of care and skill in its exercise thereof, as a prudent person
          would exercise or use under the circumstances in the conduct of his or
          her own affairs.

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

          (i)  prior to the occurrence of any Event of Default and after the
               curing or waiving of all such Events of Default that may have
               occurred:

               (A)  the duties and obligations of the Preferred Guarantee
                    Trustee shall be determined solely by the express provisions
                    of this Guarantee Agreement, and the Preferred Guarantee
                    Trustee shall not be liable except for the performance of
                    such duties and obligations as are specifically set forth in
                    this Guarantee Agreement, and no implied covenants or
                    obligations shall be read into this Guarantee Agreement
                    against the Preferred Guarantee Trustee; and

               (B)  in the absence of bad faith on the part of the Preferred
                    Guarantee Trustee, the Preferred Guarantee Trustee may
                    conclusively rely, as to the truth of the statements and the
                    correctness of the opinions expressed therein, upon any
                    certificates or opinions furnished to the Preferred
                    Guarantee Trustee and conforming to the requirements of this
                    Guarantee Agreement; but in the case of any such

                                       7
<Page>

                    certificates or opinions that by any provision hereof are
                    specifically required to be furnished to the Preferred
                    Guarantee Trustee, the Preferred Guarantee Trustee shall be
                    under a duty to examine the same to determine whether or not
                    they conform to the requirements of this Declaration;

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

         (iii) the Preferred Guarantee 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 not less than a
               Majority in liquidation amount of the Preferred Securities
               relating to the time, method and place of conducting any
               proceeding for any remedy available to the Preferred Guarantee
               Trustee, or exercising any trust or power conferred upon the
               Preferred Guarantee Trustee under this Guarantee Agreement; and

          (iv) no provision of this Guarantee Agreement shall require the
               Preferred Guarantee Trustee to expend or risk its own funds or
               otherwise incur personal financial liability in the performance
               of any of its duties or in the exercise of any of its rights or
               powers, if the Preferred Guarantee Trustee shall have reasonable
               grounds for believing that the repayment of such funds or
               liability is not reasonably assured to it under the terms of this
               Guarantee Agreement or adequate indemnity such risk or liability
               is not reasonably assured to it.

SECTION 3.2.   CERTAIN RIGHTS OF PREFERRED GUARANTEE TRUSTEE.

     (a)  Subject to the provisions of Section 3.1:

          (i)  the Preferred Guarantee Trustee may rely and shall be fully
               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, sent or
               presented by the proper party or parties;

                                       8
<Page>

          (ii) any direction or act of the Guarantor contemplated by this
               Guarantee Agreement shall be sufficiently evidenced by a
               Direction or an Officers' Certificate;

         (iii) whenever, in the administration of this Guarantee Agreement, the
               Preferred Guarantee Trustee shall deem it desirable that a matter
               be proved or established before taking, suffering or omitting any
               action hereunder, the Preferred Guarantee Trustee (unless other
               evidence is herein specifically prescribed) may, in the absence
               of bad faith on its part, request and rely upon an Officers'
               Certificate which, upon receipt of such request, shall be
               promptly delivered by the Guarantor;

          (iv) the Preferred Guarantee Trustee shall have no duty to see to any
               recording, filing or registration of any instrument (or any
               rerecording, refiling or registration thereof);

          (v)  the Preferred Guarantee Trustee may consult with counsel (which
               counsel may be counsel to the Guarantor or any of its Affiliates
               and may include any of its employees), and the written advice or
               opinion of such counsel with respect to legal matters 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 accordance with such advice or opinion, and the Preferred
               Guarantee Trustee shall have the right at any time to seek
               instructions concerning the administration of this Guarantee
               Agreement from any court of competent jurisdiction;

          (vi) the Preferred Guarantee Trustee shall be under no obligation to
               exercise any of the rights or powers vested in it by this
               Guarantee Agreement at the request or direction of any Holder,
               unless such Holder shall have provided to the Preferred Guarantee
               Trustee such adequate security and indemnity as would satisfy a
               reasonable person in the position of the Preferred Guarantee
               Trustee against the costs, expenses (including attorneys' fees
               and expenses) and liabilities that might be incurred by it in
               complying with such request or direction, including such
               reasonable advances as may be requested by the Preferred
               Guarantee Trustee; provided that, nothing contained in this
               Section 3.2(a)(vi) shall be taken to relieve the Preferred
               Guarantee Trustee, upon the occurrence of an Event of Default, of
               its obligation to exercise the rights and powers vested in it by
               this Guarantee Agreement;

         (vii) the Preferred Guarantee Trustee shall not be bound to make any
               investigation into the facts or matters stated in any resolution,

                                       9
<Page>

               certificate, statement, instrument, opinion, report, notice,
               request, direction, consent, order, bond, debenture, note, other
               evidence of indebtedness or other paper or document, but the
               Preferred Guarantee Trustee, in its discretion, may make such
               further inquiry or investigation into such facts or matters as it
               may see fit;

        (viii) the Preferred Guarantee 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 Preferred
               Guarantee 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;

          (ix) any action taken by the Preferred Guarantee Trustee or its agents
               hereunder shall bind the Holders of the Preferred Securities, and
               the signature of the Preferred Guarantee Trustee or its agents
               alone shall be sufficient and effective to perform any such
               action, and no third party shall be required to inquire as to the
               authority of the Preferred Guarantee Trustee to so act or as to
               its compliance with any of the terms and provisions of this
               Guarantee Agreement, both of which shall be conclusively
               evidenced by the Preferred Guarantee Trustee's or its agent's
               taking such action; and

          (x)  whenever in the administration of this Guarantee Agreement the
               Preferred Guarantee Trustee shall deem it desirable to receive
               instructions with respect to enforcing any remedy or right or
               taking any other action hereunder, the Preferred Guarantee
               Trustee (i) may request instructions from the Holders of the
               Preferred Securities, (ii) may refrain from enforcing such remedy
               or right or taking such other action until such instructions are
               received, and (iii) shall be protected in acting in accordance
               with such instructions.

     (b)  No provision of this Guarantee Agreement shall be deemed to impose any
          duty or obligation on the Preferred Guarantee Trustee to perform any
          act or acts or exercise any right, power, duty or obligation conferred
          or imposed on it in any jurisdiction in which it shall be illegal, or
          in which the Preferred Guarantee Trustee shall be unqualified or
          incompetent in accordance with applicable law, to perform any such act
          or acts or to exercise any such right, power, duty or obligation. No
          permissive power or authority available to the Preferred Guarantee
          Trustee shall be construed to be a duty.

SECTION 3.3.   NOT RESPONSIBLE FOR RECITALS OR ISSUANCE OF GUARANTEE. The
recitals contained in this Guarantee shall be taken as the statements of the
Guarantor, and the

                                       10
<Page>

Preferred Guarantee Trustee does not assume any responsibility for their
correctness. The Preferred Guarantee Trustee makes no representation as to
the validity or sufficiency of this Guarantee Agreement.

                                   ARTICLE IV
                           PREFERRED GUARANTEE TRUSTEE

SECTION 4.1.   PREFERRED GUARANTEE TRUSTEE; ELIGIBILITY.

     (a)  There shall at all times be a Preferred Guarantee Trustee which shall:

          (i) not be an Affiliate of the Guarantor; and

          (ii) be a corporation organized and doing business under the laws of
               the United States of America or any State or Territory thereof or
               of the District of Columbia, or a corporation or Person permitted
               by the Securities and Exchange Commission to act as an
               institutional trustee under the Trust Indenture Act, authorized
               under such laws to exercise corporate trust powers, having a
               combined capital and surplus of at least 50 million U.S. dollars
               ($50,000,000), and subject to supervision or examination by
               Federal, State, Territorial or District of Columbia authority. If
               such corporation publishes reports of condition at least
               annually, pursuant to law or to the requirements of the
               supervising or examining authority referred to above, then, for
               the purposes of this Section 4.1(a)(ii), 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.

     (b)  If at any time the Preferred Guarantee Trustee shall cease to be
          eligible to so act under Section 4.1(a), the Preferred Guarantee
          Trustee shall immediately resign in the manner and with the effect set
          out in Section 4.2(c).

     (c)  If the Preferred Guarantee Trustee has or shall acquire any
          "conflicting interest" within the meaning of Section 310(b) of the
          Trust Indenture Act, the Preferred Guarantee Trustee and Guarantor
          shall in all respects comply with the provisions of Section 310(b) of
          the Trust Indenture Act.

                                       11
<Page>

SECTION 4.2.   APPOINTMENT, REMOVAL AND RESIGNATION OF PREFERRED GUARANTEE
TRUSTEES.

     (a)  Subject to Section 4.2(b), the Preferred Guarantee Trustee may be
          appointed or removed without cause at any time by the Guarantor.

     (b)  The Preferred Guarantee Trustee shall not be removed in accordance
          with Section 4.2(a) until a Successor Preferred Guarantee Trustee has
          been appointed and has accepted such appointment by written instrument
          executed by such Successor Preferred Guarantee Trustee and delivered
          to the Guarantor.

     (c)  The Preferred Guarantee Trustee appointed to office shall hold office
          until a Successor Preferred Guarantee Trustee shall have been
          appointed or until its removal or resignation. The Preferred Guarantee
          Trustee may resign from office (without need for prior or subsequent
          accounting) by an instrument in writing executed by the Preferred
          Guarantee Trustee and delivered to the Guarantor, which resignation
          shall not take effect until a Successor Preferred Guarantee Trustee
          has been appointed and has accepted such appointment by instrument in
          writing executed by such Successor Preferred Guarantee Trustee and
          delivered to the Guarantor and the resigning Preferred Guarantee
          Trustee.

     (d)  If no Successor Preferred Guarantee Trustee shall have been appointed
          and accepted appointment as provided in this Section 4.2 within 60
          days after delivery to the Guarantor of an instrument of resignation,
          the resigning Preferred Guarantee Trustee may petition a court of
          competent jurisdiction for appointment of a Successor Preferred
          Guarantee Trustee. Such court may thereupon, after prescribing such
          notice, if any, as it may deem proper, appoint a Successor Preferred
          Guarantee Trustee.

                                   ARTICLE V
                                    GUARANTEE

SECTION 5.1.   GUARANTEE.

The Guarantor irrevocably and unconditionally agrees to pay in full to the
Holders the Guarantee Payments (without duplication of amounts theretofore paid
by the Issuer), as and when due, regardless of any defense, right of set-off or
counterclaim that the Issuer may have or assert. The Guarantor's obligation to
make a Guarantee Payment may be satisfied by direct payment of the required
amounts by the Guarantor to the Holders or by causing the Issuer to pay such
amounts to the Holders.

                                       12
<Page>

SECTION 5.2.   WAIVER OF NOTICE AND DEMAND.

The Guarantor hereby waives notice of acceptance of this Guarantee Agreement and
of any liability to which it applies or may apply, presentment, demand for
payment, any right to require a proceeding first against the Issuer or any other
Person before proceeding against the Guarantor, protest, notice of nonpayment,
notice of dishonor, notice of redemption and all other notices and demands.

SECTION 5.3.   OBLIGATIONS NOT AFFECTED

The obligations, covenants, agreements and duties of the Guarantor under this
Guarantee Agreement shall in no way be affected or impaired by reason of the
happening from time to time of any of the following:

     (a)  the release or waiver, by operation of law or otherwise, of the
          performance or observance by the Issuer of any express or implied
          agreement, covenant, term or condition relating to the Preferred
          Securities to be performed or observed by the Issuer;

     (b)  the extension of time for the payment by the Issuer of all or any
          portion of the Distributions, Redemption Price, Liquidation
          Distribution or any other sums payable under the terms of the
          Preferred Securities or the extension of time for the performance of
          any other obligation under, arising out of, or in connection with, the
          Preferred Securities (other than an extension of time for payment of
          Distributions, Redemption Price, Liquidation Distribution or other sum
          payable that results from the extension of any interest payment period
          on the Debentures or any extension of the maturity date of the
          Debentures permitted by the Indenture);

     (c)  any failure, omission, delay or lack of diligence on the part of the
          Holders to enforce, assert or exercise any right, privilege, power or
          remedy conferred on the Holders pursuant to the terms of the Preferred
          Securities, or any action on the part of the Issuer granting
          indulgence or extension of any kind;

     (d)  the voluntary or involuntary liquidation, dissolution, sale of any
          collateral, receivership, insolvency, bankruptcy, assignment for the
          benefit of creditors, reorganization, arrangement, composition or
          readjustment of debt of, or other similar proceedings affecting, the
          Issuer or any of the assets of the Issuer;

     (e)  any invalidity of, or defect or deficiency in the Preferred
          Securities;

     (f)  the settlement or compromise of any obligation guaranteed hereby or
          hereby incurred; or

                                       13
<Page>

     (g)  any other circumstance whatsoever that might otherwise constitute a
          legal or equitable discharge or defense of a guarantor, it being the
          intent of this Section 5.3 that the obligations of the Guarantor
          hereunder shall be absolute and unconditional under any and all
          circumstances.

There shall be no obligation of the Holders to give notice to, or obtain consent
of, the Guarantor with respect to the happening of any of the foregoing.

SECTION 5.4.   RIGHTS OF HOLDERS.

     (a)  The Holders of a Majority in liquidation amount of the Preferred
          Securities have the right to direct the time, method and place of
          conducting any proceeding for any remedy available to the Preferred
          Guarantee Trustee in respect of this Guarantee Agreement or exercising
          any trust or power conferred upon the Preferred Guarantee Trustee
          under this Guarantee Agreement.

     (b)  If the Preferred Guarantee Trustee fails to enforce this Guarantee
          Agreement, any Holder of Preferred Securities may, after such Holder's
          written request to the Preferred Guarantee Trustee to enforce this
          Guarantee Agreement, institute a legal proceeding directly against the
          Guarantor to enforce its rights under this Guarantee Agreement,
          without first instituting a legal proceeding against the Issuer, the
          Preferred Guarantee Trustee or any other Person.

SECTION 5.5.   GUARANTEE OF PAYMENT.

This Guarantee Agreement creates a guarantee of payment and not of collection.
The Guarantor agrees that this Guarantee Agreement shall not be discharged
except by payment of the Guarantee Payments in full and by complete performance
of all obligations of the Guarantor contained in this Guarantee Agreement.

SECTION 5.6.   SUBROGATION.

The Guarantor shall be subrogated to all (if any) rights of the Holders of
Preferred Securities against the Issuer in respect of any amounts paid to such
Holders by the Guarantor under this Guarantee Agreement; provided, however, that
the Guarantor shall not (except to the extent required by mandatory provisions
of law) be entitled to enforce or exercise any right that it may acquire by way
of subrogation or any indemnity, reimbursement or other agreement, in all cases
as a result of payment under this Guarantee Agreement, if, at the time of any
such payment, any amounts are due and unpaid under this Guarantee Agreement. If
any amount shall be paid to the Guarantor in violation of the preceding
sentence, the Guarantor agrees to hold such amount in trust for the Holders and
to pay over such amount to the Holders.

                                       14
<Page>

SECTION 5.7.   INDEPENDENT OBLIGATIONS.

The Guarantor acknowledges that its obligations hereunder are independent of the
obligations of the Issuer with respect to the Preferred Securities, and that the
Guarantor shall be liable as principal and as debtor hereunder to make Guarantee
Payments pursuant to the terms of this Guarantee Agreement notwithstanding the
occurrence of any event referred to in subsections (a) through (g), inclusive,
of Section 5.3 hereof.

                                   ARTICLE VI
                    LIMITATION OF TRANSACTIONS; SUBORDINATION

SECTION 6.1.   LIMITATION OF TRANSACTIONS.

So long as any Preferred Securities remain outstanding, if there shall have
occurred an Event of Default, or an event of which the Guarantor has actual
knowledge that, with the giving of notice or the lapse of time or both, would
constitute an event of default under the Indenture and in respect of which the
Guarantor shall not have taken reasonable steps to cure, or if the Guarantor has
given notice of its selection of an extended interest period with respect to the
Debentures and such period, or any extension thereof, is continuing, then, in
each case, (a) the Guarantor shall not declare or pay any dividend on, or make
any distribution with respect to, or redeem, purchase, acquire or make a
liquidation payment with respect to, any of its capital stock, (b) the Guarantor
shall not make any payment of interest, principal or premium, if any, on or
repay, repurchase or redeem any debt securities (including guarantees of
indebtedness for money borrowed) issued by the Guarantor which rank PARI PASSU
with or junior to the Debentures, and (c) the Guarantor shall not make any
payments with respect to any guarantee of a debt security of any of the
Guarantor's subsidiaries (including other guarantees) if such guarantee ranks
PARI PASSU with or junior to the Debentures; provided that the foregoing
restrictions in this Section 6.1(a) shall not apply to (i) repurchases,
redemptions or other acquisitions of shares of capital stock of the Guarantor
(A) in connection with any employment contract, benefit plan or other similar
arrangement with or for the benefit of any one or more employees, officers,
directors or consultants or (B) in connection with a dividend reinvestment or
stockholder stock purchase plan, (ii) the issuance of common stock of the
Guarantor (or securities convertible into or exercisable for such common stock)
as consideration in an acquisition transaction entered into prior to such
extended interest payment period, (iii) the reclassification of the capital
stock of the Guarantor or the exchange or conversion of any class or series of
Guarantor's capital stock for another class or series of Guarantor's capital
stock, provided that such reclassification, exchange or conversion does not
include any cash payments, (iv) the purchase of fractional interests in shares
of Guarantor's capital stock pursuant to the conversion or exchange provisions
of such capital stock or the security being converted or exchanged, (v) the
issuance of the capital stock of the Guarantor in connection with the exercise
of certain rights on convertible securities, (vi) any dividend in the form of
common stock, warrants, options or other rights where the dividend stock or the
stock issuable upon exercise of

                                       15
<Page>

such warrants, options or other rights is common stock, or (vii) payments by
Guarantor under this Guarantee or under any similar guarantee by Guarantor with
respect to any securities of its subsidiaries that are made on a pro rata basis
on all such guarantees, provided the proceeds from the issuance of such
securities were used to purchase junior subordinated deferrable interest
debentures issued by such subsidiary. In addition, so long as any Preferred
Securities remain outstanding, the Guarantor (i) will remain the sole direct or
indirect owner of all the outstanding Common Securities and shall not cause or
permit the Common Securities to be transferred except to the extent such
transfer is permitted under the Indenture, provided that any permitted successor
of the Guarantor under the Indenture may succeed to the Guarantor's ownership of
the Common Securities and (ii) will use its reasonable efforts to cause the
Trust to continue to be treated as a grantor trust for United States federal
income tax purposes except in connection with a distribution of Debentures.

SECTION 6.2.   RANKING.

This Guarantee Agreement will constitute an unsecured obligation of the
Guarantor and will rank (i) subordinate and junior in right of payment to all
other liabilities of the Guarantor, other than those obligations or liabilities
made PARI PASSU or subordinate by their terms, (ii) PARI PASSU with the most
senior preferred or preference stock now or hereafter issued by the Guarantor
and with any guarantee now or hereafter entered into by the Guarantor in respect
of any preferred or preference stock of any Affiliate of the Guarantor, and
(iii) senior to the Guarantor's common stock.

                                  ARTICLE VII
                                   TERMINATION

SECTION 7.1.   TERMINATION.

This Guarantee Agreement shall terminate upon (i) full payment of the Redemption
Price of all Securities, (ii) the distribution of the Debentures to the Holders
of all of the Preferred Securities or (iii) full payment of the amounts payable
in accordance with the Declaration upon liquidation of the Issuer.
Notwithstanding the foregoing, this Guarantee Agreement will continue to be
effective or will be reinstated, as the case may be, if at any time any Holder
of Preferred Securities must restore payment of any sums paid under the
Preferred Securities or under this Preferred Securities Guarantee.

                                       16
<Page>

                                  ARTICLE VIII
                                 INDEMNIFICATION

SECTION 8.1.   EXCULPATION.

     (a)  No Indemnified Person shall be liable, responsible or accountable in
          damages or otherwise to the Guarantor or any Covered Person for any
          loss, damage or claim incurred by reason of any act or omission
          performed or omitted by such Indemnified Person in good faith in
          accordance with this Guarantee Agreement and in a manner that such
          Indemnified Person reasonably believed to be within the scope of the
          authority conferred on such Indemnified Person by this Guarantee
          Agreement or by law, except that an Indemnified Person shall be liable
          for any such loss, damage or claim incurred by reason of such
          Indemnified Person's negligence or willful misconduct with respect to
          such acts or omissions.

     (b)  An Indemnified Person shall be fully protected in relying in good
          faith upon the records of the Guarantor and upon such information,
          opinions, reports or statements presented to the Guarantor by any
          Person as to matters the Indemnified Person reasonably believes are
          within such other Person's professional or expert competence and who
          has been selected with reasonable care by or on behalf of the
          Guarantor, including information, opinions, reports or statements as
          to the value and amount of the assets, liabilities, profits, losses,
          or any other facts pertinent to the existence and amount of assets
          from which Distributions to Holders of Preferred Securities might
          properly be paid.

SECTION 8.2.   INDEMNIFICATION.

     (a)  To the fullest extent permitted by applicable law, the Guarantor shall
          indemnify and hold harmless each Indemnified Person from and against
          any loss, damage or claim incurred by such Indemnified Person by
          reason of any act or omission performed or omitted by such Indemnified
          Person in good faith in accordance with this Guarantee Agreement and
          in a manner such Indemnified Person reasonably believed to be within
          the scope of authority conferred on such Indemnified Person in
          accordance with this Guarantee Agreement, except that no Indemnified
          Person shall be entitled to be indemnified in respect of any loss,
          damage or claim incurred by such Indemnified Person by reason of
          negligence or willful misconduct with respect to such acts or
          omissions.

     (b)  To the fullest extent permitted by applicable law, expenses (including
          legal fees) incurred by an Indemnified Person in defending any claim,
          demand, action, suit or proceeding shall, from time to time, be
          advanced by the Guarantor prior to the final disposition of such
          claim, demand,

                                       17
<Page>

          action, suit or proceeding upon receipt by the Guarantor of an
          undertaking by or on behalf of the Indemnified Person to repay such
          amount if it shall be determined that the Indemnified Person is not
          entitled to be indemnified as authorized in Section 8.2(a).

                                   ARTICLE IX
                                  MISCELLANEOUS

SECTION 9.1.   SUCCESSORS AND ASSIGNS.

All guarantees and agreements contained in this Guarantee Agreement shall bind
the successors, assigns, receivers, trustees and representatives of the
Guarantor and shall inure to the benefit of the Holders of the Preferred
Securities then outstanding.

SECTION 9.2.   AMENDMENTS.

Except with respect to any changes that do not materially adversely affect the
rights of Holders (in which case no consent of Holders will be required), this
Guarantee Agreement may only be amended with the prior approval of the Holders
of at least 66-2/3% in liquidation amount (including the stated amount that
would be paid on redemption, liquidation or otherwise, plus accumulated and
unpaid Distributions to the date upon which the voting percentages are
determined) of all the outstanding Preferred Securities. The provisions of
Section 12.2 of the Declaration with respect to meetings of Holders of the
Securities apply to the giving of such approval.

SECTION 9.3.   NOTICES.

All notices provided for in this Guarantee Agreement shall be in writing, duly
signed by the party giving such notice, and shall be delivered, telecopied or
mailed by registered or certified mail, as follows:

     (a)  If given to the Preferred Guarantee Trustee, at the Preferred
          Guarantee Trustee's mailing address set forth below (or such other
          address as the Preferred Guarantee Trustee may give notice of to the
          Holders of the Preferred Securities):

                 Wilmington Trust Company
                 Rodney Square North
                 1100 N. Market Street
                 Wilmington, Delaware 19890-0001
                 Attn: Corporate Trust Administration

                                       18
<Page>

     (b)  If given to the Guarantor, at the Guarantor's mailing address set
          forth below (or such other address as the Guarantor may give notice of
          to the Holders of the Preferred Securities):

                 Northwestern Corporation
                 125 S. Dakota Avenue, Suite 1100
                 Sioux Falls, South Dakota 57104

     (c)  If given to any Holder of Preferred Securities, at the address set
          forth on the books and records of the Issuer.

All such notices shall be deemed to have been given when received in person,
telecopied with receipt confirmed, or mailed by first class mail, postage
prepaid except that if a notice or other document is refused delivery or cannot
be delivered because of a changed address of which no notice was given, such
notice or other document shall be deemed to have been delivered on the date of
such refusal or inability to deliver.

SECTION 9.4.   BENEFIT.

This Guarantee Agreement is solely for the benefit of the Holders of the
Preferred Securities and the Preferred Guarantee Trustee and, subject to Section
3.1(a), is not separately transferable from the Preferred Securities.

SECTION 9.5.   GOVERNING LAW.

THIS GUARANTEE AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED AND INTERPRETED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK.

                                       19
<Page>

     THIS GUARANTEE AGREEMENT is executed as of the day and year first above
written.

                                     NORTHWESTERN CORPORATION

                                     By: /s/ Kipp D. Orme
                                         ---------------------------------------
                                     Name: Kipp D. Orme
                                     Title: Vice President--Finance and CFO

                                     WILMINGTON TRUST COMPANY,
                                     as Preferred Guarantee Trustee

                                     By: /s/ Patricia A. Evans
                                         ---------------------------------------
                                     Name: Patricia A. Evans
                                     Title: Assistant Secretary and Senior
                                            Financial Services Officer

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00032-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00032-of-00352.parquet"}]]