U.S. SUBSIDIARIES GUARANTY

                                                                    EXHIBIT 10.4

                                                                  EXECUTION COPY

                           U.S. SUBSIDIARIES GUARANTY

          SUBSIDIARIES GUARANTY (as amended, modified, restated and/or
supplemented from time to time, this "Guaranty"), dated as of December 23, 2004,
made by and among each of the undersigned guarantors (each, a "Guarantor" and,
together with any other entity that becomes a guarantor hereunder pursuant to
Section 22 hereof, collectively, the "Guarantors") in favor of Deutsche Bank
Trust Company Americas, as Administrative Agent (together with any successor
administrative agent, the "Administrative Agent"), for the benefit of the
Secured Creditors (as defined below). Except as otherwise defined herein, all
capitalized terms used herein and defined in the Credit Agreement (as defined
below) shall be used herein as therein defined.

                                  WITNESSETH:

          WHEREAS, CSA Acquisition Corp. ("Holdings"), Cooper-Standard
Automotive Inc. (the "U.S. Borrower"), Cooper-Standard Automotive Canada Limited
(the "Canadian Borrower" and, together with the U.S. Borrower, the "Borrowers"),
the Lenders from time to time party thereto (the "Lenders"), the Administrative
Agent, Lehman Commercial Paper Inc., as Syndication Agent, Goldman Sachs Credit
Partners L.P., UBS Securities LLC and The Bank of Nova Scotia, as
Co-Documentation Agents, and Deutsche Bank Securities Inc. and Lehman Brothers
Inc., as Joint Lead Arrangers and Book Runners, have entered into a Credit
Agreement, dated as of December 23, 2004 (as amended, modified, restated and/or
supplemented from time to time, the "Credit Agreement"), providing for the
making of Loans to, and the issuance of, and participation in, Letters of Credit
for the respective accounts of the Borrowers, all as contemplated therein (the
Lenders, each Issuing Lender, the Administrative Agent, the Collateral Agent,
each other Agent, the Joint Lead Arrangers and the Pledgee are herein called the
"Lender Creditors");

          WHEREAS, each Borrower and/or one or more of their respective
Subsidiaries may at any time and from time to time enter into one or more Swap
Agreements with one or more Lenders or any affiliate thereof (each such Lender
or affiliate, even if the respective Lender subsequently ceases to be a Lender
under the Credit Agreement for any reason, together with such Lender's or
affiliate's successors and assigns, if any, collectively, the "Other Creditors"
and, together with the Lender Creditors, the "Secured Creditors", with each such
Swap Agreement with an Other Creditor being herein called a "Secured Hedging
Agreement");

          WHEREAS, each Guarantor is a direct or indirect Wholly-Owned Domestic
Subsidiary of the U.S. Borrower;

          WHEREAS, it is a condition precedent to the making of Loans to the
Borrowers and the issuance of, and participation in, Letters of Credit for the
respective accounts of the Borrowers under the Credit Agreement and to the Other
Creditors entering into Secured Hedging



Agreements that each Guarantor shall have executed and delivered to the
Administrative Agent this Guaranty; and

          WHEREAS, each Guarantor will obtain benefits from the incurrence of
Loans by the Borrowers and the issuance of, and participation in, Letters of
Credit for the respective accounts of the Borrowers under the Credit Agreement
and the entering into by the Borrowers and/or one or more of their respective
Subsidiaries of Secured Hedging Agreements and, accordingly, desires to execute
this Guaranty in order to satisfy the condition described in the preceding
paragraph and to induce the Lenders to make Loans to the Borrowers and issue,
and/or participate in, Letters of Credit for the respective accounts of the
Borrowers and the Other Creditors to enter into Secured Hedging Agreements with
the Borrowers and/or one or more of their respective Subsidiaries;

          NOW, THEREFORE, in consideration of the foregoing and other benefits
accruing to each Guarantor, the receipt and sufficiency of which are hereby
acknowledged, each Guarantor hereby makes the following representations and
warranties to the Administrative Agent for the benefit of the Secured Creditors
and hereby covenants and agrees with each other Guarantor and the Administrative
Agent for the benefit of the Secured Creditors as follows:

          1. GUARANTY. (a) Each Guarantor, jointly and severally, irrevocably,
absolutely and unconditionally guarantees as a primary obligor and not merely as
surety:

          (i) to the Lender Creditors the full and prompt payment when due
     (whether at the stated maturity, by required prepayment, declaration,
     acceleration, demand or otherwise) of (x) the principal of (or, Face Amount
     of, as applicable), premium, if any, and interest on the Notes issued by,
     and the Loans made to, each of the Borrowers under the Credit Agreement,
     and all reimbursement obligations and Unpaid Drawings with respect to
     Letters of Credit and (y) all other obligations (including, without
     limitation, obligations which, but for the automatic stay under Section
     362(a) of the Bankruptcy Code, would become due), liabilities and
     indebtedness owing by each Borrower to the Lender Creditors under each
     Credit Document to which such Borrower is a party (including, without
     limitation, indemnities, Fees and interest thereon (including, without
     limitation, any interest accruing after the commencement of any bankruptcy,
     insolvency, receivership or similar proceeding at the rate provided for in
     the Credit Agreement, whether or not such interest is an allowed claim in
     any such proceeding)), whether now existing or hereafter incurred under,
     arising out of or in connection with each such Credit Document and the due
     performance and compliance by each Borrower with all of the terms,
     conditions, covenants and agreements contained in all such Credit Documents
     (all such principal (or, Face Amount, as applicable), premium, interest,
     liabilities, indebtedness and obligations under this clause (i), except to
     the extent consisting of obligations or liabilities with respect to Secured
     Hedging Agreements, being herein collectively called the "Credit Document
     Obligations"); and

          (ii) to each Other Creditor the full and prompt payment when due
     (whether at the stated maturity, by required prepayment, declaration,
     acceleration, demand or otherwise) of all obligations (including, without
     limitation, obligations which, but for the



     automatic stay under Section 362(a) of the Bankruptcy Code, would become
     due), liabilities and indebtedness (including, without limitation, any
     interest accruing after the commencement of any bankruptcy, insolvency,
     receivership or similar proceeding at the rate provided for in the
     respective Secured Hedging Agreements, whether or not such interest is an
     allowed claim in any such proceeding) owing by each Borrower and each other
     Guaranteed Party under each Secured Hedging Agreement to which it is a
     party, whether now in existence or hereafter arising, and the due
     performance and compliance by each Borrower and each such other Guaranteed
     Party with all of the terms, conditions, covenants and agreements contained
     therein (all such obligations, liabilities and indebtedness being herein
     collectively called the "Other Obligations", and together with the Credit
     Document Obligations are herein collectively called the "Guaranteed
     Obligations").

As used herein, the term "Guaranteed Party" shall mean each Borrower and each
other Subsidiary of Holdings party to any Secured Hedging Agreement. Each
Guarantor understands, agrees and confirms that the Secured Creditors may
enforce this Guaranty up to the full amount of the Guaranteed Obligations
against such Guarantor without proceeding against any other Guarantor, either
Borrower or any other Guaranteed Party, or against any security for the
Guaranteed Obligations, or under any other guaranty covering all or a portion of
the Guaranteed Obligations. This Guaranty is a guaranty of prompt payment and
performance and not of collection.

          (b) Additionally, each Guarantor, jointly and severally,
unconditionally, absolutely and irrevocably, guarantees the payment of any and
all Guaranteed Obligations whether or not due or payable by either Borrower or
any such other Guaranteed Party upon the occurrence in respect of either
Borrower or any other Guaranteed Party of any of the events specified in clauses
(h), (i) or (j) of Section 11 of the Credit Agreement, and unconditionally,
absolutely and irrevocably, jointly and severally, promises to pay such
Guaranteed Obligations to the Secured Creditors, or order, on demand.

          2. LIABILITY OF GUARANTORS ABSOLUTE. The liability of each Guarantor
hereunder is primary, absolute, joint and several, and unconditional and is
exclusive and independent of any security for or other guaranty of the
indebtedness of either Borrower or any other Guaranteed Party whether executed
by such Guarantor, any other Guarantor, any other guarantor or by any other
party, and the liability of each Guarantor hereunder shall not be affected or
impaired by any circumstance or occurrence whatsoever, including, without
limitation: (a) any direction as to application of payment by either Borrower,
any other Guaranteed Party or any other party, (b) any other continuing or other
guaranty, undertaking or maximum liability of a Guarantor or of any other party
as to the Guaranteed Obligations, (c) any payment on or in reduction of any such
other guaranty or undertaking, (d) any dissolution, termination or increase,
decrease or change in personnel by either Borrower or any other Guaranteed
Party, (e) the failure of the Guarantor to receive any benefit from or as a
result of its execution, delivery and performance of this Guaranty, (f) any
payment made to any Secured Creditor on the indebtedness which any Secured
Creditor repays either Borrower or any other Guaranteed Party pursuant to court
order in any bankruptcy, reorganization, arrangement, moratorium or other debtor
relief proceeding, and each Guarantor waives any right to the



deferral or modification of its obligations hereunder by reason of any such
proceeding, (g) any action or inaction by the Secured Creditors as contemplated
in Section 5 hereof or (h) any invalidity, rescission, irregularity or
unenforceability of all or any part of the Guaranteed Obligations or of any
security therefor.

          3. OBLIGATIONS OF GUARANTORS INDEPENDENT. The obligations of each
Guarantor hereunder are independent of the obligations of any other Guarantor,
any other guarantor, either Borrower or any other Guaranteed Party, and a
separate action or actions may be brought and prosecuted against each Guarantor
whether or not action is brought against any other Guarantor, any other
guarantor, either Borrower or any other Guaranteed Party and whether or not any
other Guarantor, any other guarantor, either Borrower or any other Guaranteed
Party be joined in any such action or actions. Each Guarantor waives (to the
fullest extent permitted by applicable law) the benefits of any statute of
limitations affecting its liability hereunder or the enforcement thereof. Any
payment by either Borrower or any other Guaranteed Party or other circumstance
which operates to toll any statute of limitations as to such Borrower or such
other Guaranteed Party shall operate to toll the statute of limitations as to
each Guarantor.

          4. WAIVERS BY GUARANTORS. (a) Each Guarantor hereby waives (to the
fullest extent permitted by applicable law) notice of acceptance of this
Guaranty and notice of the existence, creation or incurrence of any new or
additional liability to which it may apply, and waives promptness, diligence,
presentment, demand of payment, demand for performance, protest, notice of
dishonor or nonpayment of any such liabilities, suit or taking of other action
by the Administrative Agent or any other Secured Creditor against, and any other
notice to, any party liable thereon (including such Guarantor, any other
Guarantor, any other guarantor, either Borrower or any other Guaranteed Party)
and each Guarantor further hereby waives any and all notice of the creation,
renewal, extension or accrual of any of the Guaranteed Obligations and notice or
proof of reliance by any Secured Creditor upon this Guaranty, and the Guaranteed
Obligations shall conclusively be deemed to have been created, contracted or
incurred, or renewed, extended, amended, modified, supplemented or waived, in
reliance upon this Guaranty.

          (b) Each Guarantor waives any right to require the Secured Creditors
to: (i) proceed against either Borrower, any other Guaranteed Party, any other
Guarantor, any other guarantor of the Guaranteed Obligations or any other party;
(ii) proceed against or exhaust any security held from either Borrower, any
other Guaranteed Party, any other Guarantor, any other guarantor of the
Guaranteed Obligations or any other party; or (iii) pursue any other remedy in
the Secured Creditors' power whatsoever. Each Guarantor waives any defense based
on or arising out of any defense of either Borrower, any other Guaranteed Party,
any other Guarantor, any other guarantor of the Guaranteed Obligations or any
other party other than payment in full in cash of the Guaranteed Obligations,
including, without limitation, any defense based on or arising out of the
disability of either Borrower, any other Guaranteed Party, any other Guarantor,
any other guarantor of the Guaranteed Obligations or any other party, or the
unenforceability of the Guaranteed Obligations or any part thereof from any
cause, or the cessation from any cause of the liability of either Borrower or
any other Guaranteed Party other than payment in full in cash of the Guaranteed
Obligations. The Secured Creditors may, at their election, foreclose on any
collateral serving as security held by the Administrative Agent, the Collateral
Agent or the



other Secured Creditors by one or more judicial or nonjudicial sales, whether or
not every aspect of any such sale is commercially reasonable (to the extent such
sale is permitted by applicable law), or exercise any other right or remedy the
Secured Creditors may have against either Borrower, any other Guaranteed Party
or any other party, or any security, without affecting or impairing in any way
the liability of any Guarantor hereunder except to the extent the Guaranteed
Obligations have been paid in full in cash. Each Guarantor waives any defense
arising out of any such election by the Secured Creditors, even though such
election operates to impair or extinguish any right of reimbursement,
contribution, indemnification or subrogation or other right or remedy of such
Guarantor against either Borrower, any other Guaranteed Party, any other
guarantor of the Guaranteed Obligations or any other party or any security.

          (c) Each Guarantor has knowledge and assumes all responsibility for
being and keeping itself informed of each Borrower's, each other Guaranteed
Party's and each other Guarantor's financial condition, affairs and assets, and
of all other circumstances bearing upon the risk of nonpayment of the Guaranteed
Obligations and the nature, scope and extent of the risks which such Guarantor
assumes and incurs hereunder, and has adequate means to obtain from each
Borrower, each other Guaranteed Party and each other Guarantor on an ongoing
basis information relating thereto and each Borrower's, each other Guaranteed
Party's and each other Guarantor's ability to pay and perform its respective
Guaranteed Obligations, and agrees to assume the responsibility for keeping, and
to keep, so informed for so long as this Guaranty is in effect. Each Guarantor
acknowledges and agrees that (x) the Secured Creditors shall have no obligation
to investigate the financial condition or affairs of either Borrower, any other
Guaranteed Party or any other Guarantor for the benefit of such Guarantor nor to
advise such Guarantor of any fact respecting, or any change in, the financial
condition, assets or affairs of either Borrower, any other Guaranteed Party or
any other Guarantor that might become known to any Secured Creditor at any time,
whether or not such Secured Creditor knows or believes or has reason to know or
believe that any such fact or change is unknown to such Guarantor, or might (or
does) increase the risk of such Guarantor as guarantor hereunder, or might (or
would) affect the willingness of such Guarantor to continue as a guarantor of
the Guaranteed Obligations hereunder and (y) the Secured Creditors shall have no
duty to advise any Guarantor of information known to them regarding any of the
aforementioned circumstances or risks.

          (d) Each Guarantor hereby acknowledges and affirms that it understands
that to the extent the Guaranteed Obligations are secured by Real Property
located in the State of California, such Guarantor shall be liable for the full
amount of the liability hereunder notwithstanding foreclosure on such Real
Property by trustee sale or any other reason impairing such Guarantor's or any
Secured Creditors' right to proceed against either Borrower, any other
Guaranteed Party or any other guarantor of the Guaranteed Obligations.

          (e) Each Guarantor hereby waives (to the fullest extent permitted by
applicable law) until such time as the Guaranteed Obligations have been
irrevocably paid in full in cash all rights and benefits under Section 580a,
580b, 580d and 726 of the California Code of Civil Procedure. Each Guarantor
hereby further waives (to the fullest extent permitted by applicable law) until
such time as the Guaranteed Obligations have been irrevocably paid in full in
cash, without limiting the generality of the foregoing or any other provision
hereof, all rights



and benefits which might otherwise be available to such Guarantor under Sections
2809, 2810, 2815, 2819, 2821, 2839, 2845, 2848, 2849, 2850, 2899 and 3433 of the
California Civil Code.

          (f) Until the Guaranteed Obligations have been paid in full in cash,
each Guarantor waives its rights of subrogation and reimbursement and any other
rights and defenses available to such Guarantor by reason of Sections 2787 to
2855, inclusive, of the California Civil Code, including, without limitation,
(1) any defenses such Guarantor may have to this Guaranty by reason of an
election of remedies by the Secured Creditors and (2) any rights or defenses
such Guarantor may have by reason of protection afforded to either Borrower or
any other Guaranteed Party pursuant to the antideficiency or other laws of
California limiting or discharging such Borrower's or such other Guaranteed
Party's indebtedness, including, without limitation, Section 580a, 580b, 580d or
726 of the California Code of Civil Procedure. In furtherance of such
provisions, each Guarantor hereby waives all rights and defenses arising out of
an election of remedies by the Secured Creditors, even though that election of
remedies, such as a nonjudicial foreclosure, destroys such Guarantor's rights of
subrogation and reimbursement against either Borrower or any other Guaranteed
Party by the operation of Section 580d of the California Code of Civil Procedure
or otherwise.

          (g) Each Guarantor hereby acknowledges and agrees that no Secured
Creditor nor any other Person shall be under any obligation (a) to marshal any
assets in favor of such Guarantor or in payment of any or all of the liabilities
of any Guaranteed Party under the Credit Documents or the obligation of such
Guarantor hereunder or (b) to pursue any other remedy that such Guarantor may or
may not be able to pursue itself any right to which such Guarantor hereby
waives.

          (h) Each Guarantor warrants and agrees that each of the waivers set
forth in Section 3 and in this Section 4 is made with full knowledge of its
significance and consequences and that if any of such waivers are determined to
be contrary to any applicable law or public policy, such waivers shall be
effective only to the maximum extent permitted by applicable law.

          5. RIGHTS OF SECURED CREDITORS. Subject to Sections 4 and 13, any
Secured Creditor may (except as shall be required by applicable statute and
cannot be waived) at any time and from time to time without the consent of, or
notice to, any Guarantor, without incurring responsibility to such Guarantor,
without impairing or releasing the obligations or liabilities of such Guarantor
hereunder, upon or without any terms or conditions and in whole or in part:

          (a) change the manner, place or terms of payment of, and/or change,
     increase or extend the time of payment of, renew, increase, accelerate or
     alter, any of the Guaranteed Obligations (including, without limitation,
     any increase or decrease in the rate of interest thereon or the principal
     amount thereof), any security therefor, or any liability incurred directly
     or indirectly in respect thereof, and the guaranty herein made shall apply
     to the Guaranteed Obligations as so changed, extended, increased,
     accelerated, renewed or altered;



          (b) take and hold security for the payment of the Guaranteed
     Obligations and sell, exchange, release, surrender, impair, realize upon or
     otherwise deal with in any manner and in any order any property or other
     collateral by whomsoever at any time pledged or mortgaged to secure, or
     howsoever securing, the Guaranteed Obligations or any liabilities
     (including any of those hereunder) incurred directly or indirectly in
     respect thereof or hereof, and/or any offset thereagainst;

          (c) exercise or refrain from exercising any rights against either
     Borrower, any other Guaranteed Party, any other Credit Party, any
     Subsidiary thereof, any other guarantor of either Borrower or any other
     Guaranteed Party or others or otherwise act or refrain from acting;

          (d) release or substitute any one or more endorsers, Guarantors, other
     guarantors, either Borrower, any other Guaranteed Party or other obligors;

          (e) settle or compromise any of the Guaranteed Obligations, any
     security therefor or any liability (including any of those hereunder)
     incurred directly or indirectly in respect thereof or hereof, and may
     subordinate the payment of all or any part thereof to the payment of any
     liability (whether due or not) of either Borrower or any other Guaranteed
     Party to creditors of such Borrower or such other Guaranteed Party other
     than the Secured Creditors;

          (f) apply any sums by whomsoever paid or howsoever realized to any
     liability or liabilities of either Borrower or any other Guaranteed Party
     to the Secured Creditors regardless of what liabilities of such Borrower or
     such other Guaranteed Party remain unpaid;

          (g) consent to or waive any breach of, or any act, omission or default
     under, any of the Secured Hedging Agreements, the Credit Documents or any
     of the instruments or agreements referred to therein, or otherwise amend,
     modify or supplement any of the Secured Hedging Agreements, the Credit
     Documents or any of such other instruments or agreements;

          (h) act or fail to act in any manner which may deprive such Guarantor
     of its right to subrogation against either Borrower or any other Guaranteed
     Party to recover full indemnity for any payments made pursuant to this
     Guaranty; and/or

          (i) take any other action or omit to take any other action which
     would, under otherwise applicable principles of common law, give rise to a
     legal or equitable discharge of such Guarantor from its liabilities under
     this Guaranty (including, without limitation, any action or omission
     whatsoever that might otherwise vary the risk of such Guarantor or
     constitute a legal or equitable defense to or discharge of the liabilities
     of a guarantor or surety or that might otherwise limit recourse against
     such Guarantor).

No invalidity, illegality, irregularity or unenforceability of all or any part
of the Guaranteed Obligations, the Credit Documents or any other agreement or
instrument relating to the



Guaranteed Obligations or of any security or guarantee therefor shall affect,
impair or be a defense to this Guaranty, and this Guaranty shall be primary,
absolute and unconditional notwithstanding the occurrence of any event or the
existence of any other circumstances which might constitute a legal or equitable
discharge of a surety or guarantor except payment in full in cash of the
Guaranteed Obligations.

          6. CONTINUING GUARANTY. This Guaranty is a continuing one and all
liabilities to which it applies or may apply under the terms hereof shall be
conclusively presumed to have been created in reliance hereon. No failure or
delay on the part of any Secured Creditor in exercising any right, power or
privilege hereunder shall operate as a waiver thereof, nor shall any single or
partial exercise of any right, power or privilege hereunder preclude any other
or further exercise thereof or the exercise of any other right, power or
privilege. The rights and remedies herein expressly specifi