Document:

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                                                                     EXHIBIT 4.1
                                                                  EXECUTION COPY

                          Third Supplemental Indenture

                           Dated as of August 8, 2002

     This Third Supplemental Indenture to the Indenture referred to below is
dated as of August 8, 2002 (this "Supplemental Indenture") among AK Steel
Corporation, a Delaware corporation ("AK Steel"), AK Steel Holding Corporation,
a Delaware corporation ("Holding"), Douglas Dynamics, L.L.C., a Delaware limited
liability company (the "Subsidiary Guarantor"), and Fifth Third Bank, as trustee
(the "Trustee").

     AK Steel, Holding, the Subsidiary Guarantor and the Trustee are parties to
an Indenture dated as of February 10, 1999, a First Supplemental Indenture
thereto dated as of August 6, 1999 and a Second Supplemental Indenture thereto
dated as of October 1, 1999 (as so amended and supplemented by the First
Supplemental Indenture, the "Indenture") providing, among other things, for the
authentication, delivery and administration of AK Steel's 7 7/8% Senior Notes
due 2009 issued thereunder (the "Notes").

     AK Steel has solicited consents from Holders (as defined below) of the
Notes to certain amendments to the Indenture described in Article II hereof (the
"Proposed Amendments").

     Pursuant to Section 9.2 of the Indenture, the Holders of at least a
majority in principal amount of the outstanding Notes have consented in writing
to the Proposed Amendments.

     AK Steel has directed the Trustee to execute and deliver this Supplemental
Indenture in accordance with the terms of the Indenture.

     In consideration of the foregoing premises, the parties mutually agree as
follows for the benefit of each other and for the equal and ratable benefit of
the Holders of the Notes:

                                    ARTICLE I

                          DEFINITIONS AND EFFECTIVENESS

     Section 1.1   Definitions. Except as otherwise defined herein, capitalized
terms defined in the Indenture are used herein as therein defined.

     Section 1.2   Effectiveness. The Proposed Amendments will become effective
immediately upon execution and delivery hereof by each of Holding, the Company,
the Subsidiary Guarantor and the Trustee (the "Effective Time").

                                   ARTICLE II

                             AMENDMENTS TO INDENTURE

     Section 2.1   Amendments to Indenture. On and after the Effective Time, the
Indenture shall be amended as follows:

            (a)    Section 1.1 of the Indenture shall be amended to insert the
     following definition in proper alphabetical order: "`Permitted Guarantees'
     means Guarantees issued by AK Steel of up to $50.0 million aggregate
     principal amount of Debt at any one time outstanding issued by another
     Person structured as an unincorporated joint venture, partnership,
     association or limited liability company (i) in which AK Steel or any
     Wholly Owned Guarantor Subsidiary owns at least 50% of the outstanding
     total voting power of

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     Equity Interests thereof and (ii) that engages only in a business of the
     type conducted by AK Steel on the date hereof or in a business ancillary
     thereto."

          (b)     The definition of "Consolidated Net Income" contained in
     Section 1.1 of the Indenture shall be amended as follows:

                  (i)   in clause (g) thereof an "(i)" shall be inserted
          immediately before the words "special charges"; and

                  (ii)  following the last word "expenses" in clause (g) thereof
          shall be inserted the following text ", (ii) net gains or losses from
          a fourth quarter (corridor) adjustment (and related tax effects)
          recognized by Holding, AK Steel or any Subsidiary in accordance with
          its method of recording unrecognized net actuarial gains and losses in
          accounting for pensions and other postretirement benefits, provided,
          however, that if any such fourth quarter adjustment shall occur, it
          shall be included prospectively in Consolidated Net Income for
          purposes of Section 4.7 hereof to the following extent: its effect
          (and related tax effects) shall be deferred and amortized equally over
          a period of 120 months beginning January 1 of the year subsequent to
          the fourth quarter adjustment and (iii) any charges (and related tax
          effects) recorded by Holding, AK Steel or any Subsidiary as a result
          of the impairment of goodwill under generally accepted accounting
          principles".

          (c)     The definition of "Permitted Investments" contained in Section
     1.1 of the Indenture shall be amended as follows:

                  (i)   the reference to clause "(g)" thereof shall be changed
          to clause "(h)" and the word "and" immediately preceding such clause
          shall be deleted; and

                  (ii)  the following new clause (g) shall be inserted in proper
          alphabetical order: "(g) Permitted Guarantees; and".

          (d)     Section 4.5 of the Indenture shall be amended by inserting the
     following immediately prior to the period at the end of clause (h): "; or
     (i) Permitted Guarantees."

          (e)     Section 4.7 of the Indenture shall be amended as follows:

                  (i)   in clause (a)(v)(3) thereof (including subclauses (A)
                  through (D)),

                        (A)  the five references to the date "October 1, 1996"
                  shall be replaced with the date "April 1, 2002"; and

                        (B)  the following shall be inserted immediately prior
                  to the period at the end of subclause (D): ", plus (E) $25.0
                  million"; and

                  (ii)  in clause (c) thereof the reference to the date
          "February 28, 2001" shall be replaced by the date "June 30, 2004".

     Section 2.2  Notification to Holders. AK Steel shall notify the Holders in
accordance with Section 9.2 of the Indenture of the execution of this
Supplemental Indenture. Any failure of AK Steel to give such notice to all
Holders, or any defect therein, shall not impair or affect the validity of this
Supplemental Indenture.

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     Section 2.3  Receipt by Trustee. In accordance with Sections 9.6 and 11.4
of the Indenture, the parties acknowledge that the Trustee has received an
Officers' Certificate and an Opinion of Counsel as conclusive evidence that this
Supplemental Indenture complies with the applicable requirements of the
Indenture, including that the Proposed Amendments are authorized or permitted by
the Indenture.

                                   ARTICLE III

                                  MISCELLANEOUS

     Section 3.1  Parties. Nothing expressed or mentioned herein is intended or
shall be construed to give any Person, other than the Holders and the Trustee,
any legal or equitable right, remedy or claim under or in respect of this
Supplemental Indenture or the Indenture or any provision herein or therein
contained.

     Section 3.2  Governing Law. The rights and duties of AK Steel, Holding, the
Guarantor and the Trustee under this Supplemental Indenture shall, pursuant to
New York General Obligations Law Section 5-1401, be governed by the laws of the
State of New York.

     Section 3.3  Separability Clause. In case any provision in this
Supplemental Indenture shall be invalid, illegal or unenforceable, the validity,
legality and enforceability of the remaining provisions shall not in any way be
affected or impaired thereby.

     Section 3.4  Ratification of Indenture; Supplemental Indenture Part of
Indenture. Except as expressly supplemented hereby, the Indenture is in all
respects ratified and confirmed and all the terms, conditions, and provisions
thereof shall remain in full force and effect. This Supplemental Indenture shall
form a part of the Indenture for all purposes, and every Holder of Notes
heretofore or hereafter authenticated and delivered shall be bound hereby. The
Trustee makes no representation or warranty as to the validity or sufficiency of
this Supplemental Indenture.

     Section 3.5  Multiple Originals. The parties may sign any number of copies
of this Supplemental Indenture. Each signed copy shall be an original, but all
of them shall represent the same agreement. One signed copy is enough to prove
this Supplemental Indenture.

     Section 3.6  Headings. The headings of the Articles and Sections of this
Supplemental Indenture have been inserted for convenience of reference only, are
not intended to be considered a part hereof and shall not modify or restrict any
of the terms or provisions hereof.

                                        3

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

                              AK Steel Corporation

                              By: /s/ James L. Wainscott
                                  ---------------------------------
                                  Name:  James L. Wainscott
                                  Title: Chief Financial Officer

                              AK Steel Holding Corporation,
                              as Guarantor

                              By: /s/ James L. Wainscott
                                  ---------------------------------
                                  Name:  James L. Wainscott
                                  Title: Chief Financial Officer

                              Douglas Dynamics, L.L.C.,
                              as Subsidiary Guarantor

                              By: /s/ James L. Wainscott
                                  ---------------------------------
                                  Name:  James L. Wainscott
                                  Title: Treasurer

                              Fifth Third Bank,
                              as Trustee

                              By: /s/ Gregory R. Hahn
                                  ---------------------------------
                                  Name:  Gregory R. Hahn
                                  Title: Assistant Vice President

                                        4<PAGE>

                                                                     EXHIBIT 4.2

                                                                  EXECUTION COPY

                          Supplemental Indenture No. 6

                           Dated as of August 8, 2002

     This Supplemental Indenture No. 6 to the Indenture referred to below is
dated as of August 8, 2002 (this "Supplemental Indenture") between AK Steel
Corporation, a Delaware corporation (the "Company"), AK Steel Holding
Corporation, a Delaware corporation ("Holding"), Douglas Dynamics, L.L.C., a
Delaware corporation (the "Subsidiary Guarantor"), and U.S. Bank National
Association, as trustee (the "Trustee").

     The Company, Holding, the Subsidiary Guarantor and the Trustee are parties
to an Indenture dated as of November 1, 1993 (the "Base Indenture"), as amended
and supplemented by Supplemental Indenture No. 2 dated as of December 15, 1998
("Supplemental Indenture No. 2"), Supplemental Indenture No. 3 dated as of July
30, 1999, Supplemental Indenture No. 4 dated as of September 30, 1999, and
Supplemental Indenture No. 5 dated as of October 1, 1999 (the Base Indenture, as
so amended and supplemented by each of the foregoing Supplemental Indentures,
the "Indenture") providing, among other things, for the authentication, delivery
and administration of the Company's 8 7/8% Senior Notes due 2008 issued
thereunder (the "Notes").

     The Company has solicited consents from Holders (as defined below) of the
Notes to certain amendments to the Indenture described in Article II hereof (the
"Proposed Amendments").

     Pursuant to Section 10.02 of the Base Indenture, the Holders of not less
than a majority in aggregate principal amount of the outstanding Notes have
approved the Proposed Amendments.

     The Company has directed the Trustee to execute and deliver this
Supplemental Indenture in accordance with the terms of the Indenture.

     In consideration of the foregoing premises, the parties mutually agree as
follows for the benefit of each other and for the equal and ratable benefit of
the Holders of the Notes:

                                    ARTICLE I

                          DEFINITIONS AND EFFECTIVENESS

     Section 1.1   Definitions. Except as otherwise defined herein, capitalized
terms defined in the Indenture are used herein as therein defined.

     Section 1.2   Effectiveness. The Proposed Amendments will become effective
immediately upon execution and delivery hereof by each of the Company, Holding,
the Subsidiary Guarantor and the Trustee (the "Effective Time").

                                   ARTICLE II

                             AMENDMENTS TO INDENTURE

     Section 2.1   Amendments to Indenture. On and after the Effective Time, the
Indenture shall be amended as follows:

            (a)    Section 203 of Supplemental Indenture No. 2 shall be amended
     to include the following definitions in proper alphabetical order:

                   (i)    "'Permitted Guarantees' means Guarantees issued by the
            Company of up to $50.0 million aggregate principal amount of
            Indebtedness at

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          any one time outstanding issued by another Person structured as an
          unincorporated joint venture, partnership, association or limited
          liability company (i) in which the Company or any Wholly Owned
          Restricted Subsidiary owns at least 50% of the outstanding total
          Voting Stock thereof and (ii) that engages only in a business of the
          type conducted by the Company on August 8, 2002 or in a business
          ancillary thereto."; and

               (ii)  "`Wholly Owned Restricted Subsidiary' means any Restricted
          Subsidiary all the Voting Stock of which (other than directors'
          qualifying shares) is owned by the Company or another Wholly Owned
          Restricted Subsidiary of the Company."

          (b)  The definition of "Consolidated Net Income" contained in Section
     203 of the Indenture shall be amended as follows:

               (i)   clause (viii) thereof shall be deleted and the reference to
          clause "(ix)" thereof shall be changed to clause "(viii)";

               (ii)  an "(A)" shall be inserted immediately before the words
          "special charges" contained in the last clause thereof; and

               (iii) the following shall be inserted immediately prior to the
          period at the end thereof: ", (B) net gains or losses from a fourth
          quarter (corridor) adjustment (and related tax effects) recognized by
          the Company or any Subsidiary in accordance with its method of
          recording unrecognized net actuarial gains and losses in accounting
          for pensions and other postretirement benefits, provided, however,
          that if any such fourth quarter adjustment shall occur, it shall be
          included prospectively in Consolidated Net Income for purposes of
          Section 302 hereof to the following extent: its effect (and related
          tax effects) shall be deferred and amortized equally over a period of
          120 months beginning January 1 of the year subsequent to the fourth
          quarter adjustment and (C) any charges (and related tax effects)
          recorded by the Company or any Subsidiary as a result of the
          impairment of goodwill under generally accepted accounting
          principles".

          (c)  The definition of "Restricted Payment" contained in Section 203
     of the Indenture shall be amended by inserting the text "(A) Permitted
     Guarantees or (B)" in the final proviso immediately following the words
     "provided, that Restricted Payments shall not include" thereof.

          (d)  Section 302 of the Indenture shall be amended as follows:

               (i)   in clause (a)(iii) thereof,

                     (a)   the three references to the date "September 12, 1997"
          shall be replaced with the date "April 1, 2002";

                     (b)   the words "subsequent to June 30, 1997" shall be
          replaced with the words "from April 1, 2002";

                     (c)   the word "and" shall be deleted from the end of
               subclause (B); and

                                        2

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                           (d)  the following shall be inserted immediately
                   prior to the period at the end of subclause (C): "and (D)
                   $25.0 million";

                   (ii)    the word "and" shall be deleted from the end of
             clause (b)(x) thereof, ;

                   (iii)   the words "wholly owned" in clause (b)(xi) thereof
             shall be replaced by the words "Wholly Owned";

                   (iv)    the following shall be inserted immediately prior to
             the period at the end of clause (b)(xi) thereof: "; and (xii) so
             long as none of the conditions described in clause (i) and (ii) of
             subsection (a) hereof exists, declaring and paying one or more
             dividends on or before June 30, 2004 in an aggregate amount not to
             exceed $50.0 million"; and

                   (v)     the text "(vi), (ix) and (x) of Section 302(b)"
             contained in clause (c) thereof shall be replaced with the text
             "(vi), (ix), (x) and (xii) of Section 302(b)".

             (e)   Section 303 of the Indenture shall be amended as follows:

                   (i)     the word "and" shall be deleted at the end of clause
             (b)(x) thereof; and

                   (ii)    the following shall be inserted immediately prior to
             the period at the end of clause (b)(xi) thereof: "; and (xii)
             Permitted Guarantees".

     Section 2.2   Notification to Holders. The Company shall notify the Holders
of the execution of this Supplemental Indenture. Any failure of the Company to
give such notice to all Holders, or any defect therein, shall not impair or
affect the validity of this Supplemental Indenture.

     Section 2.3   Receipt by Trustee. In accordance with Sections 10.03 and
14.04 of the Base Indenture, the parties acknowledge that the Trustee has
received an Officers' Certificate and an Opinion of Counsel as conclusive
evidence that this Supplemental Indenture complies with the Indenture.

                                   ARTICLE III

                                  MISCELLANEOUS

     Section 3.1   Parties. Nothing expressed or mentioned herein is intended or
shall be construed to give any Person, other than the Holders and the Trustee,
any legal or equitable right, remedy or claim under or in respect of this
Supplemental Indenture or the Indenture or any provision herein or therein
contained.

     Section 3.2   Governing Law. This Supplemental Indenture shall be deemed to
be a contract made under the laws of the State of New York, and for all purposes
shall be construed in accordance with the laws of said State, without reference
to principles of conflicts of law.

     Section 3.3   Separability Clause. If any one or more of the provisions
contained in this Supplemental Indenture be invalid, illegal or unenforceable in
any respect, the validity, legality and enforceability of the remaining
provisions contained herein shall not in any way be affected, impaired,
prejudiced or disturbed thereby.

                                        3

<PAGE>

     Section 3.4  Ratification of Indenture; Supplemental Indenture Part of
Indenture. Except as expressly supplemented hereby, the Indenture is in all
respects ratified and confirmed and all the terms, conditions, and provisions
thereof shall remain in full force and effect. This Supplemental Indenture shall
form a part of the Indenture for all purposes, and every Holder of Notes
heretofore or hereafter authenticated and delivered shall be bound hereby. The
Trustee makes no representation or warranty as to the validity or sufficiency of
this Supplemental Indenture.

     Section 3.5  Counterparts. This Supplemental Indenture may be
simultaneously executed in several counterparts, and all such counterparts
executed and delivered, each as an original, shall constitute one and the same
instrument.

     Section 3.6  Headings. The descriptive headings of the several Articles of
this Supplemental Indenture were formulated, used and inserted in this
Supplemental Indenture for convenience only and shall not be deemed to affect
the meaning or construction of any of the provisions hereof.

                                        4

<PAGE>

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

                              Ak Steel Corporation

                              By: /s/ James L. Wainscott
                                  ---------------------------------
                                  Name:  James L. Wainscott
                                  Title: Chief Financial Officer

                              Ak Steel Holding Corporation,
                              as Guarantor

                              By: /s/ James L. Wainscott
                                  ---------------------------------
                                  Name:  James L. Wainscott
                                  Title: Chief Financial Officer

                              Douglas Dynamics, L.L.C.,
                              as Subsidiary Guarantor

                              By: /s/ James L. Wainscott
                                  ---------------------------------
                                  Name:  James L. Wainscott
                                  Title: Treasurer

                              U.S. Bank Trust National Association,
                              as Trustee

                              By: /s/ Robert T. Jones
                                  ---------------------------------
                                  Name:  Robert T. Jones
                                  Title: Vice President and Trust Officer

                                        5

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