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                                TEREX CORPORATION

                                  $100,000,000

                    8-7/8% Senior Subordinated Notes due 2008

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

                          THIRD SUPPLEMENTAL INDENTURE

                           Dated as of August 26, 1999

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

                    UNITED STATES TRUST COMPANY OF NEW YORK,

                                     Trustee



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                  THIRD  SUPPLEMENTAL  INDENTURE,  dated as of August 26,  1999,
between TEREX CORPORATION,  a Delaware  corporation (the "Company"),  and UNITED
STATES  TRUST  COMPANY OF NEW YORK,  a New York  corporation,  as  trustee  (the
"Trustee").

                  WHEREAS, the Company, and Terex Cranes, Inc., Koehring Cranes,
Inc., PPM Cranes,  Inc.,  Payhauler Corp.,  Terex-Telelect  Inc., Terex Aerials,
Inc.,  Terex-Ro  Corporation,  Terex Mining  Equipment,  Inc., O & K Orenstein &
Koppel,  Inc., The American Crane  Corporation  and Amida  Industries,  Inc., as
guarantors  (collectively,  the  "Subsidiary  Guarantors"),  and the Trustee are
parties  to an  Indenture  dated  as of  March  9,  1999,  as  amended  by First
Supplemental  Indenture  dated as of April 1, 1999,  and as  further  amended by
Second Supplemental  Indenture dated as of July 29, 1999 (said Indenture,  as it
may  heretofore  or  hereafter  from time to time be amended,  the  "Indenture")
providing for the issuance of the Company's 8-7/8% Senior Subordinated Notes due
2008 (the "Notes");

                  WHEREAS,  the  Company  has  acquired  all of the  outstanding
capital stock of Cedarapids, Inc. ("Cedarapids");

                  WHEREAS,  pursuant to the terms of the  Indenture,  Cedarapids
has become a Restricted Subsidiary organized under the laws of the United States
and, as such, the Company is required to cause Cedarapids to execute and deliver
a supplemental indenture and the Subsidiary Guarantee endorsed on the Notes; and

                  WHEREAS,  the  Company,  the  Subsidiary  Guarantors  and  the
Trustee  desire  to  amend  the  Indenture  to add  Cedarapids  as a  Subsidiary
Guarantor under the Indenture.

                  NOW,  THEREFORE,   the  Company,  the  Subsidiary  Guarantors,
Cedarapids and the Trustee agree as follows for the equal and ratable benefit of
the Holders of the Notes.

                                    ARTICLE 1

                           AMENDMENT TO THE INDENTURE

         Section 1.01.  Cedarapids  shall hereby  become a Subsidiary  Guarantor
under  the  Indenture  effective  as of the date  hereof,  and as such  shall be
entitled  to all  the  benefits  and be  subject  to all the  obligations,  of a
Subsidiary  Guarantor  thereunder.  Cedarapids  agrees  to be bound by all those
provisions of the Indenture binding upon a Subsidiary Guarantor.

                                    ARTICLE 2

                                  MISCELLANEOUS

         Section 2.01. The supplement to the Indenture  effected hereby shall be
binding upon all Holders of the Notes, their transferees and assigns.  All Notes
issued and  outstanding  on the date hereof  shall be deemed to  incorporate  by
reference or include the supplement to the Indenture effected hereby.

         Section 2.02. All terms used in this Third Supplemental Indenture which
are defined in the Indenture shall have the meanings specified in the Indenture,
unless the context of this Third Supplemental Indenture otherwise requires.


         Section 2.03. This Third Supplemental  Indenture shall become a binding
agreement between the parties when counterparts  hereof shall have been executed
and delivered by each of the parties hereto.

         Section 2.04.  This Third  Supplemental  Indenture  shall be construed,
interpreted and the rights of the parties determined in accordance with the laws
of the State of New York, as applied to contracts made and performed  within the
State of New York, without regard to principles of conflicts of law.

         Section  2.05.  This Third  Supplemental  Indenture  may be executed in
several counterparts,  each of which shall be an original and all of which shall
constitute but one and the same amendment.

         Section  2.06.  The  recitals  contained  in  this  Third  Supplemental
Indenture  are  made  by the  Company  and  not by the  Trustee  and  all of the
provisions  contained in the  Indenture,  in respect of the rights,  privileges,
immunities,  powers and duties of the  Trustee  shall be  applicable  in respect
thereof as fully and with like effect as if set forth herein in full.

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

                                       TEREX CORPORATION



                                       By:/s/ Joseph F. Apuzzo
                                         Name:  Joseph F. Apuzzo
ATTEST:                                  Title: Vice President-Corporate Finance

/s/ Eric I Cohen
Eric I Cohen, Secretary



                                       UNITED STATES TRUST COMPANY
                                         OF NEW YORK, as Trustee


                                       By: /s/ John Guiliano
                                        Name: John Guiliano
ATTEST:                                 Title: Vice President

/s/ Sirojni Dindial





                (Signature Page to Third Supplemental Indenture)


                                       SUBSIDIARY GUARANTORS:

                                       KOEHRING CRANES, INC.



                                       By:/s/ Joseph F. Apuzzo
                                         Name:  Joseph F. Apuzzo
ATTEST:                                  Title:    Treasurer

/s/ Eric I Cohen
Eric I Cohen, Secretary


                                       PPM CRANES, INC.


                                       By:/s/ Joseph F. Apuzzo
                                         Name:  Joseph F. Apuzzo
ATTEST:                                  Title:    Treasurer

/s/ Eric I Cohen
Eric I Cohen, Secretary


                                       TEREX-TELELECT INC.


                                       By:/s/ Joseph F. Apuzzo
                                         Name:  Joseph F. Apuzzo
ATTEST:                                  Title:    Treasurer

/s/ Eric I Cohen
Eric I Cohen, Secretary


                                       TEREX AERIALS INC.


                                       By:/s/ Joseph F. Apuzzo
                                         Name:  Joseph F. Apuzzo
ATTEST:                                  Title:    Treasurer

/s/ Eric I Cohen
Eric I Cohen, Secretary





                (Signature Page to Third Supplemental Indenture)


                                       THE AMERICAN CRANE CORPORATION


                                       By:/s/ Joseph F. Apuzzo
                                         Name:  Joseph F. Apuzzo
ATTEST:                                  Title:    Vice President

/s/ Eric I Cohen
Eric I Cohen, Secretary


                                       TEREX-RO CORPORATION


                                       By:/s/ Joseph F. Apuzzo
                                         Name:  Joseph F. Apuzzo
ATTEST:                                  Title:    Treasurer

/s/ Eric I Cohen
Eric I Cohen, Secretary



                                       TEREX CRANES, INC.


                                       By:/s/ Joseph F. Apuzzo
                                         Name:  Joseph F. Apuzzo
ATTEST:                                  Title:    Treasurer

/s/ Eric I Cohen
Eric I Cohen, Secretary



                                       PAYHAULER CORP.


                                       By:/s/ Joseph F. Apuzzo
                                         Name:  Joseph F. Apuzzo
ATTEST:                                  Title:    Treasurer

/s/ Eric I Cohen
Eric I Cohen, Secretary





                (Signature Page to Third Supplemental Indenture)

                                       CEDARAPIDS, INC.


                                       By:/s/ Joseph F. Apuzzo
                                         Name:  Joseph F. Apuzzo
ATTEST:                                  Title:    Treasurer

/s/ Eric I Cohen
Eric I Cohen, Secretary