Exhibit 10.42

AAM LOGO [k84920aamlogo.gif]

February 26, 2004

Mr. Bo Andersson
Vice President — Worldwide Purchasing
Production Control & Logistics
General Motors Corporation
30009 Van Dyke, MC 480-206-114
Warren, Michigan 48090

Dear Bo:

This letter will confirm our agreement relative to GM’s sourcing of the
following product programs to AAM as the sole-source, exclusive Tier I supplier
and systems integrator for all of GM’s requirements for driveline components,
systems, modules and forged products for each of the following programs, and all
derivatives thereof based on each respective platform, for the life of each
program as set forth below.

1.   [XXXXX]* series program and all derivatives:   a)   GM hereby sources to
AAM as set forth above the [XXXXX]* series program and all derivatives.   b)  
Prices for [XXXXX]* series program products, which are carryover from the
[XXXXX]* series program, shall be based on the current prices of the products
being replaced, increased or decreased by the cost of engineering changes
ordered by GM in the specifications for such products.   c)   With respect to
potential non-carryover products (e.g., IRDA, Modules), AAM is hereby designated
as the development and productive source for such content. AAM and GM will work
cooperatively to minimize the costs of these products to the mutual satisfaction
of both parties based on an agreed upon design direction.   d)   AAM will
provide the following minimum annual productivity commitments on AAM content,
excluding directed buys, beginning in the second full year of production at the
following rates: [XXXXX].* AAM and GM will work cooperatively together on joint
cost reduction initiatives.   e)   In the event that the [XXXXX]* series program
utilizes a module application, either GM or AAM /GM will jointly source the
module components that AAM elects not to produce.

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*   Any text removed pursuant to AAM’s confidential treatment request has been
separately submitted with the U.S. Securities and Exchange Commission and is
marked “[XXXXX]” herein.

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2.   [XXXXXX]* Series Program   a)   GM hereby sources to AAM as set forth above
the [XXXXX]* series program and all derivatives.   b)   Prices for [XXXXX]*
series program products, which are carryover from the [XXXXX]* series program,
shall be based on the current prices of the products being replaced or modified,
increased or decreased by the cost of engineering changes ordered by GM in the
specifications for such products. To avoid uncertainty, as a derivative, any
productivity commitments of AAM for the [XXXXX]* program shall apply to the
[XXXXX]* program.   c)   With respect to potential non-carryover products (e.g.,
IRDA, Modules), AAM is hereby designated as the development and productive
source for such content. AAM and GM will work cooperatively to minimize the
costs of these products to the mutual satisfaction of both parties based on an
agreed upon design direction.   d)   In the event that the [XXXXX]* series
program utilizes a module application, either GM or AAM /GM will jointly source
the module components that AAM elects not to produce.   3.   [XXXXX]*:   a)  
AAM and GM engineering will work cooperatively together to develop an acceptable
design direction for [XXXXX]* for the [XXXXX]* and [XXXXX]* series programs and
all derivatives.   b)   If a mutually acceptable design direction is developed
within the next 60 days, then GM shall designate AAM as the exclusive source for
the [XXXXX]* for the [XXXXX]* and [XXXXX]* series programs and all derivatives.
  c)   AAM and GM will work cooperatively to minimize the costs of these
products to the mutual satisfaction of both parties based on an agreed upon
design direction.   4.   [XXXXX]* Program   a)   In the event that an acceptable
design direction for [XXXXX]* is not developed within the next 60 days, then GM
shall immediately source to AAM the front axle for the [XXXXX]* program and all
derivatives and the front /rear axle and all modules for the [XXXXX]* program
and all derivatives.   b)   Prices for such products shall be based on AAM’s
North American quotation for IRDA (August 1, 2003) and Front Axle (February 12,
2004). AAM and GM will work cooperatively to minimize the costs of these
products to the mutual satisfaction of both parties based upon an agreed upon
design direction.

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*   Any text removed pursuant to AAM’s confidential treatment request has been
separately submitted with the U.S. Securities and Exchange Commission and is
marked “[XXXXX]” herein.

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5.   Lifetime Program Contracts (LPC’s)   a)   All of the products being sourced
to AAM by GM pursuant to this agreement shall be included in AAM’s Lifetime
Program Contracts (LPC’s).   6.   Program Cancellation   a)   In the event that
any of the above product programs sourced by GM to AAM are not approved or are
canceled, other programs of equivalent value satisfactory to AAM will be
promptly sourced by GM to AAM based on the same terms and conditions as the
parties have previously agreed.   7.   Substitute Business   a)   AAM and GM
agree that GM’s $[XXXXX]* Substitute Business sourcing obligation to AAM is
fully satisfied upon the signing of this agreement.

Sincerely,

/s/ Joel D. Robinson

Joel D. Robinson
President & Chief Operating Officer

Acknowledged and Agreed to:

General Motors Corporation

/s/ Bo I. Andersson

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Bo I. Andersson
Vice President – Worldwide Purchasing
Production Control & Logistics

     
cc:
  G. Briggs – GM

  A. Ryan – GM

  D. C. Dauch – AAM

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*   Any text removed pursuant to AAM’s confidential treatment request has been
separately submitted with the U.S. Securities and Exchange Commission and is
marked “[XXXXX]” herein.

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