FIRST SUPPLEMENTAL INDENTURE


          FIRST SUPPLEMENTAL INDENTURE, (this "Supplemental Indenture") dated as
of the 21st day of September, 2000, by and among Pierce Western Region
Refurbishment Center, Inc., a California corporation ("Pierce") and an indirect
wholly owned subsidiary of Oshkosh Truck Corporation, a Wisconsin corporation
(the "Company"), Kewaunee Fabrications, L.L.C., a Wisconsin limited liability
company, and a wholly-owned subsidiary of the Company ("Kewaunee"), Viking Truck
& Equipment Sales, Inc., a Michigan corporation and an indirect wholly-owned
subsidiary of the Company ("Viking Michigan"), Viking Truck & Equipment Sales,
Inc., an Ohio corporation and an indirect wholly-owned subsidiary of the Company
("Viking Ohio"), McNeilus Financial Services, Inc., a Minnesota corporation and
an indirect wholly-owned subsidiary of the Company ("McNeilus"), Viking
Equipment Leasing, Inc., a Michigan corporation and an indirect wholly-owned
subsidiary of the Company ("Viking Leasing"), and McNeilus Rescue Corporation, a
Wisconsin corporation and an indirect wholly-owned subsidiary of the Company
("McNeilus Rescue") (each of Pierce, Kewaunee, Viking Michigan, Viking Ohio,
McNeilus, Viking Equipment and McNeilus Rescue a "Guaranteeing Subsidiary" and
collectively the "Guaranteeing Subsidiaries"), the Company, the other Subsidiary
Guarantors (as defined in the Indenture referred to herein) and Firstar Bank,
National Association, as successor in interest to Firstar Trust Company, as
trustee under the Indenture (the "Trustee").

                               W I T N E S S E T H

          WHEREAS, the Company has heretofore executed and delivered to the
Trustee an indenture (the "Indenture"), dated as of February 26, 1998 providing
for the issuance of an aggregate principal amount of up to $150,000,000 of 8
3/4% Senior Subordinated Notes due 2008 (the "Notes");

          WHEREAS, the Indenture provides that under certain circumstances a
Guaranteeing Subsidiary shall execute and deliver to the Trustee a supplemental
indenture pursuant to which such Guaranteeing Subsidiary shall unconditionally
guarantee all of the Company's Obligations under the Notes and the Indenture on
the terms and conditions set forth herein (the "Subsidiary Guarantee"); and

          WHEREAS, pursuant to Section 9.01 of the Indenture, the Trustee is
authorized to execute and deliver this Supplemental Indenture.

          NOW THEREFORE, in consideration of the foregoing and for other good
and valuable consideration, the receipt of which is hereby acknowledged, each
Guaranteeing Subsidiary and the Trustee mutually covenant and agree for the
equal and ratable benefit of the Holders of the Notes as follows:

          1. Capitalized Terms. Capitalized terms used herein without definition
shall have the meanings assigned to them in the Indenture.

<PAGE>

          2. Agreement to Guarantee. Each Guaranteeing Subsidiary hereby agrees
as follows:

          (a)  Along with all Subsidiary Guarantors named in the Indenture, to
               jointly and severally Guarantee to each Holder of a Note
               authenticated and delivered by the Trustee and to the Trustee and
               its successors and assigns, irrespective of the validity and
               enforceability of the Indenture, the Notes or the obligations of
               the Company hereunder or thereunder, that:

               (i)  The principal of and interest on the Notes will be promptly
                    paid in full when due, whether at maturity, by acceleration,
                    redemption or otherwise, and interest on the overdue
                    principal of and interest on the Notes, if any, if lawful,
                    and all other obligations of the Company to the Holders or
                    the Trustee hereunder or thereunder will be promptly paid in
                    full or performed, all in accordance with the terms hereof
                    and thereof; and

               (ii) In case of any extension of time of payment or renewal of
                    any Notes or any of such other obligations, that same will
                    be promptly paid in full when due or performed in accordance
                    with the terms of the extension or renewal, whether at
                    stated maturity, by acceleration or otherwise. Failing
                    payment when due of any amount so guaranteed or any
                    performance so guaranteed for whatever reason, the
                    Subsidiary Guarantors shall be jointly and severally
                    obligated to pay the same immediately.

          (b)  The obligations hereunder shall be unconditional, irrespective of
               the validity, regularity or enforceability of the Notes or the
               Indenture, the absence of any action to enforce the same, any
               waiver or consent by any Holder of the Notes with respect to any
               provisions hereof or thereof, the recovery of any judgment
               against the Company, an action to enforce the same or any other
               circumstance which might otherwise constitute a legal or
               equitable discharge or defense of a Subsidiary Guarantor.

          (c)  The following is hereby waived: diligence, presentment, demand of
               payment, filing of claims with a court in the event of insolvency
               or bankruptcy of the Company, any right to require a proceeding
               first against the Company, protest, notice and all demands
               whatsoever.

          (d)  This Note Guarantee shall not be discharged except by complete
               performance of the obligations contained in the Notes and the
               Indenture.

          (e)  If any Holder or the Trustee is required by any court or
               otherwise to return to the Company, the Subsidiary Guarantors, or
               any Custodian, Trustee, liquidator or other similar official
               acting in relation to either the


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<PAGE>

               Company or the Subsidiary Guarantors, any amount paid by either
               to the Trustee or such Holder, this Subsidiary Guarantee, to the
               extent theretofore discharged, shall be reinstated in full force
               and effect.

          (f)  No Subsidiary Guarantor shall be entitled to any right of
               subrogation in relation to the Holders in respect of any
               obligations guaranteed hereby until payment in full of all
               obligations guaranteed hereby.

          (g)  As between the Subsidiary Guarantors, on the one hand, and the
               Holders and the Trustee, on the other hand, (x) the maturity of
               the obligations guaranteed hereby may be accelerated as provided
               in Article 6 of the Indenture for the purposes of this Subsidiary
               Guarantee, notwithstanding any stay, injunction or other
               prohibition preventing such acceleration in respect of the
               obligations guaranteed hereby, and (y) in the event of any
               declaration of acceleration of such obligations as provided in
               Article 6 of the Indenture, such obligations (whether or not due
               and payable) shall forthwith become due and payable by the
               Subsidiary Guarantors for the purpose of this Subsidiary
               Guarantee.

          (h)  The Subsidiary Guarantors shall have the right to seek
               contribution from any non-paying Subsidiary Guarantor so long as
               the exercise of such right does not impair the rights of the
               Holders under the Guarantee.

          (i)  Pursuant to Section 10.02 of the Indenture, after giving effect
               to any maximum amount and any other contingent and fixed
               liabilities that are relevant under any applicable bankruptcy or
               fraudulent conveyance laws, and after giving effect to any
               collections from, rights to receive contribution from or payments
               made by or on behalf of any other Subsidiary Guarantor in respect
               of the obligations of such other Subsidiary Guarantor under
               Article 10 of the Indenture shall result in the obligations of
               such Subsidiary Guarantor under its Subsidiary Guarantee not
               constituting a fraudulent transfer or conveyance.

          3. Execution And Delivery. Each Guaranteeing Subsidiary agrees that
the Subsidiary Guarantees shall remain in full force and effect notwithstanding
any failure to endorse on each Note a notation of such Subsidiary Guarantee.

          4. Guaranteeing Subsidiaries May Consolidate, Etc. on Certain Terms.

          (a)  No Guaranteeing Subsidiary may consolidate with or merge with or
               into (whether or not such Subsidiary Guarantor is the surviving
               Person) another corporation, Person or entity whether or not
               affiliated with such Subsidiary Guarantor unless:

               (i)  subject to Section 10.05 of the Indenture, the Person formed
                    by or surviving any such consolidation or merger (if other
                    than a Subsidiary Guarantor or the Company) unconditionally
                    assumes


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<PAGE>

                    all the obligations of such Subsidiary Guarantor, pursuant
                    to a supplemental indenture in form and substance reasonably
                    satisfactory to the Trustee, under the Notes, the Indenture
                    and the Subsidiary Guarantee on the terms set forth herein
                    or therein; and

               (ii) immediately after giving effect to such transaction, no
                    Default or Event of Default exists.

          (b)  In case of any such consolidation, merger, sale or conveyance and
               upon the assumption by the successor corporation, by supplemental
               indenture, executed and delivered to the Trustee and satisfactory
               in form to the Trustee, of the Subsidiary Guarantee endorsed upon
               the Notes and the due and punctual performance of all of the
               covenants and conditions of the Indenture to be performed by the
               Subsidiary Guarantor, such successor corporation shall succeed to
               and be substituted for the Subsidiary Guarantor with the same
               effect as if it had been named herein as a Subsidiary Guarantor.
               Such successor corporation thereupon may cause to be signed any
               or all of the Subsidiary Guarantees to be endorsed upon all of
               the Notes issuable hereunder which theretofore shall not have
               been signed by the Company and delivered to the Trustee. All the
               Subsidiary Guarantees so issued shall in all respects have the
               same legal rank and benefit under the Indenture as the Subsidiary
               Guarantees theretofore and thereafter issued in accordance with
               the terms of the Indenture as though all of such Subsidiary
               Guarantees had been issued at the date of the execution hereof.

          (c)  Except as set forth in Articles 4 and 5 of the Indenture, and
               notwithstanding clauses (a) and (b) above, nothing contained in
               the Indenture or in any of the Notes shall prevent any
               consolidation or merger of a Subsidiary Guarantor with or into
               the Company or another Subsidiary Guarantor, or shall prevent any
               sale or conveyance of the property of a Subsidiary Guarantor as
               an entirety or substantially as an entirety to the Company or
               another Subsidiary Guarantor.

          5. Releases.

          (a)  In the event of a sale or other disposition of all of the assets
               of any Subsidiary Guarantor, by way of merger, consolidation or
               otherwise, or a sale or other disposition of all to the capital
               stock of any Subsidiary Guarantor, then such Subsidiary Guarantor
               (in the event of a sale or other disposition, by way of merger,
               consolidation or otherwise, of all of the capital stock of such
               Subsidiary Guarantor) or the corporation acquiring the property
               (in the event of a sale or other disposition of all or
               substantially all of the assets of such Subsidiary Guarantor)
               will be released and relieved of any obligations under its
               Subsidiary Guarantee; provided that the Net Proceeds of such sale
               or other disposition are


                                       -4-
<PAGE>

               applied in accordance with the applicable provisions of the
               Indenture, including without limitation Section 4.10 of the
               Indenture. Upon delivery by the Company to the Trustee of an
               Officers' Certificate and an Opinion of Counsel to the effect
               that such sale or other disposition was made by the Company in
               accordance with the provisions of the Indenture, including
               without limitation Section 4.10 of the Indenture, the Trustee
               shall execute any documents reasonably required in order to
               evidence the release of any Subsidiary Guarantor from its
               obligations under its Subsidiary Guarantee.

          (b)  Any Subsidiary Guarantor not released from its obligations under
               its Subsidiary Guarantee shall remain liable for the full amount
               of principal of and interest on the Notes and for the other
               obligations of any Subsidiary Guarantor under the Indenture as
               provided in Article 10 of the Indenture.

          6. No Recourse Against Others. No past, present or future director,
officer, employee, incorporator, stockholder or agent of each Guaranteeing
Subsidiary, as such, shall have any liability for any obligations of the Company
or any Guaranteeing Subsidiary under the Notes, any Subsidiary Guarantees, the
Indenture or this Supplemental Indenture or for any claim based on, in respect
of, or by reason of, such obligations or their creation. Each Holder of the
Notes by accepting a Note waives and releases all such liability. The waiver and
release are part of the consideration for the issuance of the Notes. Such waiver
may not be effective to waive liabilities under the federal securities laws and
it is the view of the Commission that such a waiver is against public policy.

          7. New York Law to Govern. THE INTERNAL LAW OF THE STATE OF NEW YORK
SHALL GOVERN AND BE USED TO CONSTRUE THIS SUPPLEMENTAL INDENTURE BUT WITHOUT
GIVING EFFECT TO APPLICABLE PRINCIPLES OF CONFLICTS OF LAW TO THE EXTENT THAT
THE APPLICATION OF THE LAWS OF ANOTHER JURISDICTION WOULD BE REQUIRED THEREBY.

          8. Counterparts. The parties may sign any number of copies of this
Supplemental Indenture. Each signed copy shall be an original, but all of them
together represent the same agreement.

          9. Effect Of Headings. The Section headings herein are for convenience
only and shall not affect the
construction hereof.

          10. The Trustee. The Trustee shall not be responsible in any manner
whatsoever for or in respect of the validity or sufficiency of this Supplemental
Indenture or for or in respect of the recitals contained herein, all of which
recitals are made solely by each Guaranteeing Subsidiary and the Company.


                                       -5-
<PAGE>

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

                                        OSHKOSH TRUCK CORPORATION


                                        By: /s/ Scott L. Ney
                                            ----------------------------------
                                        Name:  Scott L. Ney
                                        Title:  Vice President and Treasurer


                                        PIERCE WESTERN REGION
                                        REFURBISHMENT CENTER, INC.


                                        By: /s/ Scott L. Ney
                                            ----------------------------------
                                        Name:  Scott L. Ney
                                        Title:  Vice President and Treasurer


                                        KEWAUNEE FABRICATIONS, L.L.C.


                                        By: /s/ Scott L. Ney
                                            ----------------------------------
                                        Name:  Scott L. Ney
                                        Title:  Vice President and Treasurer


                                        VIKING TRUCK & EQUIPMENT SALES, INC.,
                                        a  Michigan corporation

                                        By: /s/ Scott L. Ney
                                            -----------------------------------
                                        Name:  Scott L. Ney
                                        Title:  Vice President and Treasurer


                                        VIKING TRUCK & EQUIPMENT SALES, INC.,
                                        an Ohio corporation


                                        By: /s/ Scott L. Ney
                                            -----------------------------------
                                        Name:  Scott L. Ney
                                        Title:  Vice President and Treasurer


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<PAGE>

                                        MCNEILUS FINANCIAL SERVICES, INC.


                                        By: /s/ Scott L. Ney
                                            -----------------------------------
                                        Name:  Scott L. Ney
                                        Title:  Vice President and Treasurer


                                        VIKING EQUIPMENT LEASING, INC.


                                        By: /s/ Scott L. Ney
                                            -----------------------------------
                                        Name:  Scott L. Ney
                                        Title:  Vice President and Treasurer


                                        MCNEILUS RESCUE CORPORATION


                                        By: /s/ Scott L. Ney
                                            -----------------------------------
                                        Name:  Scott L. Ney
                                        Title:  Vice President and Treasurer


                                        MCNEILUS TRUCK & MANUFACTURING, INC.


                                        By: /s/ Scott L. Ney
                                            -----------------------------------
                                        Name:  Scott L. Ney
                                        Title:  Vice President and Treasurer


                                        IOWA CONTRACT FABRICATORS, INC.


                                        By: /s/ Scott L. Ney
                                            -----------------------------------
                                        Name:  Scott L. Ney
                                        Title:  Vice President and Treasurer


                                       -7-
<PAGE>

                                        MCINTIRE FABRICATORS, INC.


                                        By: /s/ Scott L. Ney
                                            -----------------------------------
                                        Name:  Scott L. Ney
                                        Title:  Vice President and Treasurer


                                        KENSETT FABRICATORS, INC.


                                        By: /s/ Scott L. Ney
                                            -----------------------------------
                                        Name:  Scott L. Ney
                                        Title:  Vice President and Treasurer


                                        MCNEILUS COMPANIES, INC.


                                        By: /s/ Scott L. Ney
                                            -----------------------------------
                                        Name:  Scott L. Ney
                                        Title:  Vice President and Treasurer


                                        MCNEILUS FINANCIAL, INC.


                                        By: /s/ Scott L. Ney
                                            -----------------------------------
                                        Name:  Scott L. Ney
                                        Title:  Vice President and Treasurer


                                        PIERCE MANUFACTURING, INC.


                                        By: /s/ Scott L. Ney
                                            -----------------------------------
                                        Name:  Scott L. Ney
                                        Title:  Vice President and Treasurer

                                        SUMMIT PERFORMANCE SYSTEMS, INC.


                                        By: /s/ Scott L. Ney
                                            -----------------------------------
                                        Name:  Scott L. Ney
                                        Title:  Vice President and Treasurer


                                       -8-
<PAGE>

                                        FIRSTAR BANK, NATIONAL ASSOCIATION,
                                        as Trustee


                                        By:
                                            -----------------------------------
                                        Name:__________________________________
                                        Title:_________________________________




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