Document:

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                                                                    Exhibit 10.8

                                                                [Execution Copy]

                            PIPELINE HOLDCO GUARANTY

      This Guaranty dated as of May 3, 2004, (the "Guaranty") is by WILLIAMS GAS
PIPELINE COMPANY, LLC, a Delaware limited liability company ("Guarantor"), in
favor of Citicorp USA, Inc., solely in its capacity as collateral agent
("Collateral Agent") for the Financial Institutions (as defined below).

                                  INTRODUCTION

      A.    The Williams Companies, Inc., a Delaware corporation (the
"Company"), Northwest Pipeline Corporation, a Delaware corporation ("NWP"), and
Transcontinental Gas Pipe Line Corporation, a Delaware corporation ("TGPL", and
together with TWC and NWP, the "Borrowers"), have entered into a Credit
Agreement dated as of May 3, 2004 (as amended or otherwise modified from time to
time, the "Credit Agreement", the defined terms from the Credit Agreement are
used in this Guaranty as defined therein unless otherwise defined herein),
together with Citicorp USA, Inc., as administrative agent and collateral agent
("Collateral Agent"), Bank of America, N.A., as syndication agent ("Syndication
Agent"), Citibank, N.A. and Bank of America, N.A., as issuing banks ("Issuing
Banks"), the banks named therein (the "Banks"), JPMorgan Chase Bank, The Bank of
Nova Scotia and The Royal Bank of Scotland PLC as co-documentation agents
(collectively, the "Co-Documentation Agents") and Citigroup Global Markets Inc.
and Banc of America Securities LLC, as joint lead arrangers and co-book runners
(collectively, the "Co-Arrangers"), providing for the extension of credit and
the issuance of Letters of Credit. The Collateral Agent, Syndication Agent,
Issuing Banks, Banks, Co-Documentation Agents and Co-Arrangers and each of the
successors and permitted assigns of the foregoing are collectively referred to
herein as the "Financial Institutions".

      B.    It is a condition to certain transactions under the Credit
Documents, that the Guarantor shall have executed and delivered this Guaranty.

      C.    The Company is the principal financing entity for all capital
requirements of some of its Subsidiaries, and from time to time the Company has
made capital contributions and advances to the Guarantor. The Guarantor is a
wholly owned Subsidiary of the Company and will derive substantial direct or
indirect benefit from the transactions contemplated by the Credit Documents.

      THEREFORE, in order to induce the Financial Institutions to enter into
and/or continue certain financing transactions described in the Credit
Documents, the Guarantor hereby agrees for the benefit of the Financial
Institutions as follows:

Section 1.  Guaranty. Guarantor hereby unconditionally and irrevocably
guarantees the punctual payment when due, whether at stated maturity, by
acceleration or otherwise, of the Guaranteed Obligations (defined below). For
purposes of this Guaranty, the term "Guaranteed Obligations" shall mean
collectively (a) all obligations under this Guaranty and (b) all Obligations (as
such term is defined by the Credit Agreement) including, without limitation, the
outstanding principal amount of indebtedness, reimbursement obligations for
draws on letters of credit, and cash collateralization obligations for letters
of credit under the Credit Documents, all accrued but unpaid interest thereon
under the Credit Documents, all premiums, if any, in

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connection therewith under the Credit Documents, all fees in connection
therewith under the Credit Documents, and all other reimbursement,
indemnification, and other payment obligations in connection therewith under the
Credit Documents; provided that Guaranteed Obligations shall not include any
increases which occur after the date hereof in the principal amount of the
obligations under the Credit Documents (other than (i) increases in the
principal amount of such obligations that are provided for as of the date of the
execution of this Agreement but not yet funded and (ii) increases contemplated
by Section 2.19 of the Credit Agreement) and/or the commitments to advance funds
or letters of credit thereunder. Without limiting the generality of the
foregoing, Guarantor's liability shall extend to all amounts which constitute
part of the Guaranteed Obligations even if such Guaranteed Obligations are
declared unenforceable or not allowable in a bankruptcy, reorganization, or
similar proceeding involving any Borrowers, or any guarantor of any portion of
the foregoing Guaranteed Obligations (collectively such guarantors together with
the Guarantor and the Borrowers are referred to herein as the "Obligors"). This
Guaranty is a guarantee of payment, not of collection, and Guarantor is
primarily liable for the payment of the Guaranteed Obligations. In the event
that Collateral Agent wishes to enforce the guarantee contained in this Section
1 hereof against Guarantor, it shall make written demand for payment from
Guarantor, provided that no such demand shall be required if Guarantor is in
bankruptcy, liquidation, or other insolvency proceedings, and provided that
failure by Collateral Agent to make such demand shall not affect Guarantor's
obligations under this Guaranty.

Section 2.  Limit of Liability. The liabilities and obligations of the Guarantor
under the Credit Documents shall be limited to an aggregate amount equal to the
largest amount that would not render such Guarantor's obligations hereunder
subject to avoidance under Section 548 of the United States Bankruptcy Code or
any comparable provisions of any applicable state law.

Section 3.  Guaranty Absolute. Guarantor guarantees that the Guaranteed
Obligations will be paid strictly in accordance with the Credit Documents,
regardless of any law, regulation, or order now or hereafter in effect in any
jurisdiction affecting any of the obligations described in clause (b) of Section
1 above or the rights of the Collateral Agent or any other Financial Institution
with respect thereto. The obligations of Guarantor under this Guaranty are
independent of the Guaranteed Obligations in each and every particular, and a
separate action or actions may be brought and prosecuted against any other
Obligor, or any other Person regardless of whether any other Obligor or any
other Person is joined in any such action or actions. The liability of Guarantor
under this Guaranty shall be absolute and unconditional irrespective of:

      (a)   The lack of validity or unenforceability of the Guaranteed
Obligations or any Credit Document (other than this Guaranty against the
Guarantor) for any reason whatsoever, including that the act of creating the
Guaranteed Obligations is ultra vires, that the officers or representatives
executing the documents creating the Guaranteed Obligations exceeded their
authority, that the Guaranteed Obligations violate usury or other laws, or that
any Obligor has defenses to the payment of the Guaranteed Obligations, including
breach of warranty, statute of frauds, bankruptcy, statute of limitations,
lender liability, or accord and satisfaction;

      (b)   Any change in the time, manner, or place of payment of, or in any
term of, any of the Guaranteed Obligations, any increase (subject to Section 1),
reduction, extension, or rearrangement of the Guaranteed Obligations, any
amendment, supplement, or other modification of the Credit Documents, or any
waiver or consent granted under the Credit Documents, including waivers of the
payment and performance of the Guaranteed Obligations;

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      (c)   Any release, exchange, subordination, waste, or other impairment
(including negligent, willful, unreasonable, or unjustifiable impairment) of any
collateral securing payment of the Guaranteed Obligations; the failure of
Collateral Agent, any other Financial Institution or any other person to
exercise diligence or reasonable care in the preservation, protection,
enforcement, sale, or other handling of the collateral; the fact that any
security interest, lien, or assignment related to any collateral for the
Guaranteed Obligations shall not be properly perfected, or shall prove to be
unenforceable or subordinate to any other security interest, lien, or
assignment;

      (d)   Any full or partial release of any Obligor (other than the full or
partial release of the Guarantor);

      (e)   The failure to apply or the manner of applying collateral or
payments of the proceeds of collateral against the Guaranteed Obligations;

      (f)   Any change in the organization or structure of any Obligor; any
change in the shareholders, directors, or officers of any Obligor; or the
insolvency, bankruptcy, liquidation, or dissolution of any Obligor or any
defense that may arise in connection with or as a result of any such insolvency,
bankruptcy, liquidator or dissolution;

      (g)   The failure to give notice of any extension of credit made by
Collateral Agent or any other Financial Institution to any Obligor, notice of
acceptance of this Guaranty, notice of any amendment, supplement, or other
modification of any Credit Document, notice of the execution of any document or
agreement creating new Guaranteed Obligations, notice of any default or event of
default, however denominated, under the Credit Documents, notice of intent to
demand, notice of demand, notice of presentment for payment, notice of
nonpayment, notice of intent to protest, notice of protest, notice of grace,
notice of dishonor, notice of intent to accelerate, notice of acceleration,
notice of bringing of suit, notice of Collateral Agent or any other Financial
Institution's transfer of the Guaranteed Obligations, notice of the financial
condition of or other circumstances regarding any Obligor, or any other notice
of any kind relating to the Guaranteed Obligations;

      (h)   Any payment or grant of collateral by any Obligor to Collateral
Agent or any other Financial Institution being held to constitute a preference
under bankruptcy laws, or for any reason Collateral Agent or any other Financial
Institution is required to refund such payment or release such collateral;

      (i)   Any other action taken or omitted which affects the Guaranteed
Obligations, whether or not such action or omission prejudices the Guarantor or
increases the likelihood that the Guarantor will be required to pay the
Guaranteed Obligations pursuant to the terms hereof;

      (j)   The fact that all or any of the Guaranteed Obligations cease to
exist by operation of law, including, without limitation, by way of discharge,
limitation or tolling thereof under applicable bankruptcy laws; and

      (k)   Any other circumstances which might otherwise constitute a defense
available to, or a discharge of any Obligor (other than the discharge of the
Guarantor or the satisfaction of the Guaranteed Obligations).

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Section 4.  Collateral Agent's Rights and Certain Waivers.

      4.01. Notice and Other Remedies. Guarantor hereby waives promptness,
diligence, notice of acceptance, notice of acceleration, notice of intent to
accelerate, and any other notice with respect to any of the Guaranteed
Obligations and this Guaranty and any requirement that Collateral Agent or any
other Financial Institution protect, secure, perfect or insure any security
interest or other Lien or any property subject thereto or exhaust any right to
take any action against any Obligor or any other Person or any collateral.

      4.02. Waiver of Subrogation and Contribution. (a) Until such time as the
Guaranteed Obligations are irrevocably paid in full, Guarantor hereby
irrevocably waives any claim or other rights which it may acquire against any
Obligor that arise from the Guarantor's Guaranteed Obligations under this
Guaranty or any other Credit Document, including, without limitation, any right
of subrogation (including, without limitation, any statutory rights of
subrogation under Section 509 of the Bankruptcy Code, 11 U.S.C. Section 509),
reimbursement, exoneration, contribution, indemnification, or any right to
participate in any claim or remedy of Collateral Agent or any other Financial
Institution against any Obligor, or any collateral which Collateral Agent or any
other Financial Institution now has or acquires. If any amount shall be paid to
Guarantor in violation of the preceding sentence and the Guaranteed Obligations
shall not have been paid in full, such amount shall be held in trust for the
benefit of Collateral Agent and the Financial Institutions, and shall promptly
be paid to the Collateral Agent for the benefit of Collateral Agent and the
other Financial Institutions to be applied to the Guaranteed Obligations,
whether matured or unmatured, as Collateral Agent may elect. Guarantor
acknowledges that it will receive direct and indirect benefits from the
financing arrangements contemplated by the Credit Documents and that the waiver
set forth in this Section 4.02(a) is knowingly made in contemplation of such
benefits.

      (b)   Guarantor agrees that, to the extent that any Borrower makes
payments to Collateral Agent or any other Financial Institution, or Collateral
Agent or any other Financial Institution receives any proceeds of collateral,
and such payments or proceeds or any part thereof are subsequently invalidated,
declared to be fraudulent or preferential, set aside, or otherwise required to
be repaid, then to the extent of such repayment the Guaranteed Obligations shall
be reinstated and continued in full force and effect as of the date such initial
payment or collection of proceeds occurred. GUARANTOR SHALL INDEMNIFY COLLATERAL
AGENT AND EACH FINANCIAL INSTITUTION AND EACH AFFILIATE THEREOF AND THEIR
RESPECTIVE DIRECTORS, OFFICERS, EMPLOYEES AND AGENTS FROM, AND DISCHARGE,
RELEASE, AND HOLD EACH OF THEM HARMLESS AGAINST, ANY AND ALL LOSSES,
LIABILITIES, PENALTIES, ACTIONS, JUDGMENTS, SUITS, COSTS, DISBURSEMENTS, CLAIMS
OR DAMAGES TO WHICH ANY OF THEM MAY BECOME SUBJECT, INSOFAR AS SUCH LOSSES,
LIABILITIES, PENALTIES, ACTIONS, JUDGMENTS, SUITS, COSTS, DISBURSEMENTS, CLAIMS
OR DAMAGES ARISE OUT OF OR RESULT FROM (I) ANY ACTUAL OR PROPOSED USE BY ANY
BORROWER, OR ANY AFFILIATE OF ANY BORROWER OF THE PROCEEDS OF ANY ADVANCE, (II)
ANY BREACH BY GUARANTOR OF ANY PROVISION OF THIS GUARANTY OR ANY OTHER CREDIT
DOCUMENT, (III) ANY INVESTIGATION, LITIGATION OR OTHER PROCEEDING (INCLUDING ANY
THREATENED INVESTIGATION OR PROCEEDING) RELATING TO THE FOREGOING, OR (IV) ANY
ENVIRONMENTAL CLAIM OR REQUIREMENT OF ENVIRONMENTAL LAWS CONCERNING OR RELATING
TO THE PRESENTLY OR PREVIOUSLY-OWNED OR OPERATED PROPERTIES, OR THE OPERATIONS
OR BUSINESS, OF ANY OBLIGOR, AND GUARANTOR SHALL REIMBURSE COLLATERAL AGENT AND
EACH FINANCIAL INSTITUTION, AND EACH AFFILIATE THEREOF AND THEIR RESPECTIVE
DIRECTORS, OFFICERS, EMPLOYEES AND AGENTS, UPON DEMAND FOR ANY REASONABLE
OUT-OF-POCKET EXPENSES (INCLUDING

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LEGAL FEES) INCURRED IN CONNECTION WITH ANY SUCH INVESTIGATION, LITIGATION OR
OTHER PROCEEDING; AND SUCH INDMENIFICATION AND REIMBURSEMENT OBLIGATIONS
EXPRESSLY INCLUDE ANY SUCH LOSSES, LIABILITIES, PENALTIES, ACTIONS, JUDGMENTS,
SUITS, COSTS, DISBURSEMENTS, CLAIMS, DAMAGES, OR EXPENSE INCURRED BY REASON OF
THE NEGLIGENCE (OTHER THAN GROSS NEGLIGENCE) OF THE PERSON BEING INDEMNIFIED,
BUT EXCLUDE ANY SUCH LOSSES, LIABILITIES, PENALTIES, ACTIONS, JUDGMENTS, SUITS,
COSTS, DISBURSEMENTS, CLAIMS, DAMAGES OR EXPENSES INCURRED BY REASON OF THE
GROSS NEGLIGENCE OR WILLFUL MISCONDUCT OF THE PERSON TO BE INDEMNIFIED.

      Collateral Agent shall have the absolute right to make demands, file suits
and claims, engage in other proceedings and exercise any other rights or
remedies available to Collateral Agent to collect amounts owed to it pursuant to
the terms of the indemnities set forth in this Guaranty, and Collateral Agent
shall not need the consent of any other Financial Institution or Person
whatsoever to do so.

      4.03. Modifications and Amendment to the Credit Documents. As provided in
Section 1 above, certain increases in the principal indebtedness outstanding
under the Credit Documents shall not constitute Guaranteed Obligations. Except
as to the foregoing, the parties to the Credit Documents shall have the right to
amend or modify such Credit Documents without affecting the rights provided for
in this Guaranty.

Section 5.  Representations, Warranties and Covenants. The representations,
warranties and covenants as are made by the Borrowers and by and on behalf of
the Guarantor under the Credit Documents are hereby deemed made and incorporated
into this Agreement each as though set forth in its entirety herein.

Section 6.  Miscellaneous.

      6.01. Amendments; Waivers. Any amendment or waiver to this Guaranty or any
provision hereof shall only be effective to the extent such amendment or waiver
(a) complies with all of those requirements set forth in Section 8.1 of the
Credit Agreement and (b) is executed by the Persons that would be required to
execute a like amendment of the Credit Agreement. Furthermore, all amendments
and waivers to this Guaranty will be subject to the limitations and restrictions
applicable to amendments and waivers of the Credit Agreement.

      6.02. Notices. All notices and other communications to Guarantor shall be
delivered to the address set forth beneath its signature on the signature page
hereto, or to such other address as shall be designated by the Guarantor by
written notice to the Collateral Agent. All notices and other communications
provided for under this Guaranty shall be in writing (including telecopy
communication), shall be mailed, telecopied, or delivered, and shall, when
mailed or telecopied, be effective when received in the mail or sent by
telecopier.

      6.03. No Waiver; Remedies. No failure on the part of Collateral Agent or
any other Financial Institution to exercise, and no delay in exercising, any
right hereunder shall operate as a waiver thereof, nor shall any single or
partial exercise of any right hereunder preclude any other or further exercise
thereof or the exercise of any other right. The remedies herein provided are
cumulative and not exclusive of any remedies provided by law.

      6.04. Right of Set-Off. Upon the occurrence and during the continuance of
any Event of Default, and (ii) either (a) the Revolving Credit Advances owed by
any Borrower having

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become due and payable in accordance with the terms of the Credit Agreement or
(b) the making of the request or the granting of the consent specified by
Section 6.1 of the Credit Agreement to authorize the Agent to declare the
Revolving Credit Advances owed by any Borrower due and payable pursuant to the
provisions of Section 6.1 of the Credit Agreement, each of Collateral Agent and
the other Financial Institutions is hereby authorized at any time, to the
fullest extent permitted by law, to set off and apply any deposits (general or
special, time or demand, provisional or final) and other indebtedness owing by
Collateral Agent or such Financial Institution to the accounts of the Guarantor
against any and all of the obligations of the Guarantor under this Guaranty,
irrespective of whether or not such Financial Institution shall have made any
demand under this Guaranty and although such obligations may be contingent and
unmatured. Collateral Agent and each Financial Institution agree promptly to
notify the Guarantor after any such set-off and application made by Collateral
Agent or such Financial Institution provided that the failure to give such
notice shall not affect the validity of such set-off and application. The rights
of Collateral Agent and the Financial Institutions under this Section 6.04 are
in addition to any other rights and remedies (including, without limitation,
other rights of set-off) which the Financial Institutions may have.

      6.05. Continuing Guaranty; Assignments under Credit Documents. This
Guaranty is a continuing guaranty and shall (a) remain in full force and effect
until the indefeasible payment in full of the Guaranteed Obligations and all
other amounts payable under this Guaranty, (b) be binding upon Guarantor and its
respective successors and assigns, (c) inure to the benefit of, and be
enforceable by, Collateral Agent and each of the Financial Institutions and
their respective successors, transferees and permitted assigns, and (d) not be
terminated by Guarantor or any other Person. Without limiting the generality of
the foregoing clause (c), Collateral Agent and any other Financial Institution
may assign or otherwise transfer all or any portion of its rights and
obligations under this Guaranty and the assignee shall thereupon become vested
with all the benefits in respect thereof granted to Collateral Agent or such
Financial Institution herein or otherwise, provided that such assignment shall
be subject to the limitations on assignments set forth in the Credit Agreement.
Upon the indefeasible payment in full and termination of the Guaranteed
Obligations, each guaranty granted hereby shall terminate and all rights
hereunder shall revert to the Guarantor to the extent such rights have not been
applied pursuant to the terms hereof. Upon any such termination, Collateral
Agent will, at Guarantor's expense, execute and deliver to Guarantor such
documents as Guarantor shall reasonably request and take any other actions
reasonably requested to evidence or effect such termination. This Guaranty is
not assignable by Guarantor without the written consent of Collateral Agent.

      6.06  Governing Law; Submission to Jurisdiction; Damages; Suits and
Claims.

      (a)   This Guaranty shall be governed by, and construed and enforced in
accordance with, the laws of the State of New York, except to the extent
provided in Section 6.06(b) hereof and to the extent that the federal laws of
the United States of America may otherwise apply.

      (b)   Notwithstanding anything in Section 6.06(a) hereof to the contrary,
nothing in this Guaranty shall be deemed to constitute a waiver of any rights
which Collateral Agent or any of the Financial Institutions may have under the
National Bank Act or other federal law, including without limitation the right
to charge interest at the rate permitted by the laws of the State where
Collateral Agent or any other applicable Financial Institution is located.

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      (c)   ANY LITIGATION BASED HEREON, OR ARISING OUT OF, UNDER, OR IN
CONNECTION WITH, ANY CREDIT DOCUMENT, OR ANY COURSE OF CONDUCT, COURSE OF
DEALING, STATEMENTS (WHETHER ORAL OR WRITTEN) OR ACTIONS OF COLLATERAL AGENT,
THE FINANCIAL INSTITUTIONS OR GUARANTOR IN CONNECTION HEREWITH OR THEREWITH MAY
BE BROUGHT AND MAINTAINED IN THE COURTS OF THE STATE OF NEW YORK OR IN THE
UNITED STATES DISTRICT COURT FOR THE SOUTHERN DISTRICT OF NEW YORK; PROVIDED,
HOWEVER, THAT ANY SUIT SEEKING ENFORCEMENT AGAINST ANY COLLATERAL OR OTHER
PROPERTY MAY BE BROUGHT, AT COLLATERAL AGENT'S OPTION, IN THE COURTS OF ANY
JURISDICTION WHERE SUCH COLLATERAL OR OTHER PROPERTY MAY BE FOUND. GUARANTOR
IRREVOCABLY CONSENTS TO THE SERVICE OF PROCESS BY REGISTERED MAIL, POSTAGE
PREPAID, OR BY PERSONAL SERVICE WITHIN OR WITHOUT THE STATE OF NEW YORK AT THE
ADDRESS SET FORTH BENEATH ITS SIGNATURE ON THE SIGNATURE PAGE HERETO. GUARANTOR
HEREBY EXPRESSLY AND IRREVOCABLY WAIVES, TO THE FULLEST EXTENT PERMITTED BY LAW,
ANY OBJECTION WHICH IT MAY HAVE OR HEREAFTER MAY HAVE TO THE LAYING OF VENUE OF
ANY SUCH LITIGATION BROUGHT IN ANY SUCH COURT REFERRED TO ABOVE AND ANY CLAIM
THAT ANY SUCH LITIGATION HAS BEEN BROUGHT IN AN INCONVENIENT FORUM. TO THE
EXTENT THAT GUARANTOR HAS OR HEREAFTER MAY ACQUIRE ANY IMMUNITY FROM
JURISDICTION OF ANY COURT OR FROM ANY LEGAL PROCESS (WHETHER THROUGH SERVICE OR
NOTICE, ATTACHMENT PRIOR TO JUDGMENT, ATTACHMENT IN AID OF EXECUTION OR
OTHERWISE) WITH RESPECT TO ITSELF OR ITS PROPERTY, GUARANTOR HEREBY IRREVOCABLY
WAIVES TO THE FULLEST EXTENT PERMITTED BY LAW SUCH IMMUNITY IN RESPECT OF ITS
OBLIGATIONS UNDER THIS GUARANTY AND THE CREDIT DOCUMENTS. EACH OF GUARANTOR, THE
COLLATERAL AGENT, AND THE FINANCIAL INSTITUTIONS HEREBY IRREVOCABLY AND
UNCONDITIONALLY WAIVES, TO THE FULLEST EXTENT IT MAY EFFECTIVELY DO SO UNDER
APPLICABLE LAW, ANY RIGHT IT MAY HAVE TO CLAIM OR RECOVER IN ANY ACTION OR
PROCEEDING REFERRED TO IN THIS SECTION 6.06 ANY EXEMPLARY, PUNITIVE SPECIAL OR
CONSEQUENTIAL DAMAGES; PROVIDED THAT NOTHING HEREIN SHALL CONSTITUTE A WAIVER BY
THE COLLATERAL AGENT, OR ANY OTHER FINANCIAL INSTITUTIONS OF THE RIGHT TO
RECEIVE FULL PAYMENT OF THE GUARANTEED OBLIGATIONS.

      (d)   GUARANTOR, COLLATERAL AGENT AND THE FINANCIAL INSTITUTIONS HEREBY
IRREVOCABLY WAIVE ANY AND ALL RIGHT TO TRIAL BY JURY IN ANY LEGAL PROCEEDING
ARISING OUT OF OR RELATING TO THIS GUARANTY OR ANY OF THE TRANSACTIONS
CONTEMPLATED HEREBY.

      (e)   The provisions set forth in this Guaranty shall only be enforceable
by the Financial Institutions and their respective successors and permitted
assigns, and no other Person shall have the right to bring any claim or cause of
action based on this Guaranty.

      6.08. Survival. All agreements, statements, representations and warranties
made by the Guarantors herein or in any certificate or other instrument
delivered by the Guarantors or on the behalf of the Guarantors under this
Guaranty shall be considered to have been relied upon by Collateral Agent and
the Financial Institutions and shall survive the execution and delivery of this
Guaranty and the other Credit Documents regardless of any investigation made by
Collateral Agent or any other Financial Institution or on their behalf.

      6.09. Headings Descriptive. The headings of the various articles, sections
and paragraphs of this Guaranty are for convenience of reference only, do not
constitute a part hereof and shall not affect the meaning or construction of any
provision hereof.

      6.10. Severability. In the event any one or more of the provisions
contained in this Guaranty or in any Security Document should be held invalid,
illegal or unenforceable in any

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respect, the validity, legality and enforceability of the remaining provisions
contained herein and therein shall not in any way be affected or impaired
thereby. The parties shall endeavor in good-faith negotiations to replace the
invalid, illegal or unenforceable provisions with valid provisions the economic
effect of which comes as close as possible to that of the invalid, illegal or
unenforceable provisions.

                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]

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<PAGE>

      Guarantor has caused this Guaranty to be duly executed as of the date
first above written.

                                          WILLIAMS GAS PIPELINE COMPANY, LLC

                                          By:    /s/ Travis N. Campbell
                                              ----------------------------------
                                          Name:    Travis N. Campbell
                                          Title:   Assistant Treasurer

                                               Address for Notices:
                                               One Williams Center
                                               Attn: Treasurer
                                               Tulsa, OK 74172

                  [SIGNATURE PAGE TO PIPELINE HOLDERS GUARANTY]<PAGE>

                                                                    EXHIBIT 10.1

                               AMENDMENT NO. 3 TO
                SUPPLEMENTAL PROFIT SHARING PLAN FOR EMPLOYEES OF
               TRINITY INDUSTRIES, INC. AND CERTAIN AFFILIATES AS
                       RESTATED EFFECTIVE JANUARY 1, 2000

      WHEREAS, TRINITY INDUSTRIES, INC., a Delaware corporation (the "Company"),
has heretofore adopted the SUPPLEMENTAL PROFIT SHARING PLAN FOR EMPLOYEES OF
TRINITY INDUSTRIES, INC. AND CERTAIN AFFILIATES AS RESTATED EFFECTIVE JANUARY 1,
2000 ("the Plan") for the benefit of certain executive and managerial employees;
and

      WHEREAS, pursuant to those provisions of the Plan permitting the Company
to amend the Plan from time to time, the Company desires to amend the Plan in
certain respects as hereinafter provided;

      NOW THEREFORE, the Plan is hereby amended as follows, effective as of
January 1, 2004:

1.    Section 4.01(b) is hereby amended to be and read as follows:

            "(b)  Matching Employer Contribution. For Plan Years beginning prior
                  to January 1, 2004, for each Year, each Employer shall credit
                  a Matching Employer Contribution amount in the form of Stock
                  Units to each of its Employees for whom an amount was credited
                  pursuant to paragraph (a) of this Section 4.01; effective for
                  Plan Years beginning on and after January 1, 2004, such a
                  Matching Employer Contribution shall be credited in cash;
                  provided, however, that no such Matching Employer Contribution
                  shall be credited prior to the date on which such Employee
                  completes one (1) year of Service. Such Matching Employer
                  Contribution, when added to the Forfeitures which have become
                  available for application as of the end of the Year pursuant
                  to Section 4.03 hereof, shall be equal to a percentage of that
                  portion of the Participant's Compensation Reduction
                  Contribution for such Year pursuant to Section 4.02 hereof
                  which does not exceed six percent (6%) of his Base
                  Compensation plus Annual Incentive Compensation for such Year,
                  based on his years of Service as follows:

<PAGE>

<TABLE>
<CAPTION>
Years of Service          Applicable Percentage
-----------------         ---------------------
<S>                       <C>
Less than 1                         0%
1 but less than 2                  25%
2 but less than 3                  30%
3 but less than 4                  35%
4 but less than 5                  40%
5 or more                          50%
</TABLE>

                  For purposes of determining a Participant's Matching Employer
                  Contribution under this paragraph (b), if a Participant's
                  Employment Commencement Date is any date on or after January
                  1, 2001 and on or before March 31, 2001, and such Participant
                  is employed as of the last day of the Short Plan Year, he
                  shall be credited with a year of Service for such Short Plan
                  Year."

2.    Section 4.01(c) is hereby amended to be and read as follows:

            "(c)  Additional Matching Contribution. For Plan Years beginning
                  prior to January 1, 2004, for each Year, each Employer shall
                  credit an additional amount in the form of Stock Units to each
                  of its Employees for whom an amount was credited pursuant to
                  paragraph (a) of this Section 4.01, which when added to the
                  Forfeitures which have become available for application as of
                  the end of the Year pursuant to Section 4.03 hereof and which
                  have not been applied as provided in paragraph (b) of this
                  Section, shall be equal to seventeen and one-half percent
                  (17-1/2%) of that portion of the Participant's Compensation
                  Reduction Contribution for such Year pursuant to Section 4.02
                  hereof which is invested or deemed invested in Stock Units
                  pursuant to Section 5.02(a) hereof up to twenty-five percent
                  (25%) of the sum of his Base Compensation and Annual Incentive
                  Compensation for such Year. Effective for Plan Years beginning
                  on and after January 1, 2004, this paragraph (c) shall have no
                  further force or effect."

In accordance with the last sentence in the revised section 4.01(c) above,
references in the Plan to Additional Matching Contributions and Additional
Matching Contribution Accounts are applicable to such contributions and accounts
prior to January 1, 2004.

3.    Section 4.01(e) is hereby amended to be and read as follows:

            "(e)  Discretionary Contributions. For Plan Years beginning prior to
                  January 1, 2004, in addition to the contributions described
                  above, for each Year an Employer may, but shall not be
                  required to, credit the Discretionary

                                        2

<PAGE>

                  Contribution Account of any one or more Participants in its
                  employ during such Year with such amounts in the form of Stock
                  Units or otherwise as the Employer may determine in its sole
                  discretion. Effective for Plan Years beginning on and after
                  January 1, 2004, if such amounts are credited, they shall be
                  credited in cash."

4.    Section 5.02 is hereby amended to be and read as follows:

      "5.02 Investment of Accounts

            (a)   Participant Election. The Committee shall credit each
                  Participant's Accounts with earnings or losses according to
                  the hypothetical investment selections made by the Participant
                  pursuant to his participation agreement executed pursuant to
                  Section 3.03 hereof. In accordance with certain limitations on
                  investment designations in Section 5.02(b), the Committee
                  shall adopt rules concerning the manner in which a Participant
                  may elect to change his hypothetical investment selections,
                  provided that a Participant shall be permitted to do so no
                  less frequently than as of the first day of each month.

                  For Plan Years beginning prior to January 1, 2004, the
                  earnings or losses attributable to a Participant's Accounts
                  shall be determined as if the amounts credited to such
                  Accounts were actually invested in Stock Units, to the extent
                  required or elected hereunder, and, to the extent not so
                  required or elected, in the hypothetical investments selected
                  under the Participant's participation agreement. In the case
                  of a Participant receiving installment payments under Article
                  VI hereof, the Participant's Accounts will continue to receive
                  allocations of earnings or losses in accordance with this
                  subsection until his Accounts are paid in full. If a
                  Participant's participation agreement fails to designate one
                  or more hypothetical investment selections, the Participant's
                  Account will be deemed invested in Stock Units, to the extent
                  required hereunder, and, to the extent not so required, in the
                  investment option designated as having the least investment
                  risk.

                  Effective for Plan Years beginning on and after January 1,
                  2004, the earnings or losses attributable to a Participant's
                  Accounts shall be determined as if the amounts credited to
                  such Accounts were actually invested in Stock Units, to the
                  extent elected hereunder, and, to the extent not so elected or
                  to the extent prohibited hereunder, in the hypothetical
                  investments selected under the Participant's participation
                  agreement. In the case of a Participant receiving installment
                  payments under Article VI hereof, the Participant's Accounts
                  will continue to receive allocations of earnings or losses in
                  accordance with this subsection until his Accounts are paid in
                  full. If a Participant's participation agreement fails to
                  designate one or more hypothetical investment selections, the
                  Participant's Account will be deemed invested in the
                  investment option designated as having the least investment
                  risk.

                                        3

<PAGE>

            (b)   Investment Options. The Committee shall have sole and absolute
                  discretion with respect to the number and types of investment
                  options made available for selection by Participants pursuant
                  to this Section, the timing of Participant elections and the
                  method by which adjustments are made. The Committee may in its
                  sole discretion refuse to recognize Participant elections that
                  it determines may cause the Participant's Accounts to become
                  subject to the short-swing profit provisions of Section 16b of
                  the Securities Exchange Act of 1934 and establish special
                  election procedures for Participants subject to Section 16 of
                  such Act.

                  For Plan Years beginning prior to January 1, 2004, the
                  Committee shall permit Participants to designate that their
                  investments be treated as invested in (i) Stock Units or (ii)
                  one or more investment indices; provided that amounts credited
                  on or after the Effective Date to a Participant's Matching
                  Contribution Account or Additional Matching Contribution
                  Account shall at all times be invested in Stock Units;
                  provided further that Compensation Reduction Contributions
                  made on or after the Effective Date of Award Compensation
                  shall at all times be invested in Stock Units.

                  Effective for Plan Years beginning on and after January 1,
                  2004, amounts credited to a Participant's Matching
                  Contribution Account and Discretionary Contribution Account
                  shall at no time be treated as invested in Stock Units. For
                  Plan Years beginning on and after January 1, 2004,
                  Compensation Reduction Contributions may, at the Participant's
                  election, be treated as invested in Stock Units, provided
                  however, that following deemed investment in any media, such
                  Contributions may not be treated as transferred into or out of
                  deemed investments in Stock Units. For Plan Years beginning on
                  and after January 1, 2004, a Participant may not designate
                  that amounts credited to his Matching Contribution Account,
                  Additional Matching Contribution Account, Discretionary
                  Contribution Account, or Compensation Reduction Contribution
                  Account and deemed invested in any media be treated as
                  transferred into or out of deemed investments in Stock Units.

                  The designation of investment options by the Committee shall
                  be for the sole purpose of adjusting Accounts pursuant to this
                  Section, and except to the extent that deemed investment in
                  Stock Units was required hereunder for Plan Years beginning
                  prior to January 1, 2004, the provisions of this Article V
                  shall not obligate the Company or any of the Employers to
                  invest or set aside any assets for the payment of benefits
                  hereunder; provided, however, that the Company or an Employer
                  may invest a portion of its general assets in investments,
                  including investments which are the same as or similar to the
                  investment indices designated by the Committee and selected by
                  Participants, but any such investments shall remain part of
                  the general assets of the Company or such Employer and shall
                  not be deemed or construed to grant a property interest of any
                  kind to any Participant, designated Beneficiary or estate. The
                  Committee shall

                                        4

<PAGE>

                  notify the Participants of the investment indices available
                  and the procedures for making and changing elections.

            (c)   Non-Binding Status of Elections. A Participant's hypothetical
                  investment selections pursuant to the immediately preceding
                  paragraph shall be made solely for purposes of crediting
                  earnings and/or losses to his Accounts under Section 5.03 of
                  this Plan. The Committee shall not, in any way, be bound to
                  actually invest any amounts set aside pursuant to Article VII
                  below to satisfy its obligations under this Plan in accordance
                  with such selections."

5.    Section 5.03(c) is hereby amended to be and read as follows:

            "(c)  Matching Contributions. For Plan Years beginning prior to
                  January 1, 2004, any Stock Units credited to a Participant by
                  an Employer pursuant to Section 4.01(b) or (c) during a Year
                  shall be allocated, as the case may be, to the Participant's
                  Matching Contribution Account or the Participant's Additional
                  Matching Contribution Account at such time as may be
                  determined by the Employer in its absolute discretion, but no
                  earlier than the last day of such Year.

                  Effective for Plan Years beginning on and after January 1,
                  2004, any amounts credited to a Participant by an Employer
                  pursuant to Section 4.01(b) during a Year shall be allocated
                  to the Participant's Matching Contribution Account at such
                  time as may be determined by the Employer in its absolute
                  discretion, but no earlier than the last day of such Year."

6.    Section 5.04(a) is hereby amended to be and read as follows:

            "(a)  General. For purposes of calculating the number of Stock Units
                  credited or deemed credited to a Participant's Accounts
                  pursuant to Section 5.03(b) and, for Plan Years beginning
                  prior to January 1, 2004, Section 5.03(d), the price of a
                  Stock Unit shall be equal to one hundred percent (100%) of the
                  closing price on the New York Stock Exchange of a share of the
                  Company's common stock on the date on which the Stock Units
                  are credited or deemed credited to the Participant's Accounts
                  (or if no shares of the Company's common stock are traded on
                  such date, on the immediately preceding trading date). For
                  Plan Years beginning prior to January 1, 2004, for purposes of
                  calculating the number of Stock Units credited to a
                  Participant's Accounts as an Employer Matching Contribution or
                  Additional Matching Contribution, the price of a Stock Unit
                  shall be equal to one hundred percent (100%) of the average
                  daily closing price on the New York Stock Exchange of a Share
                  of the Company's common stock for the Year with respect to
                  which the Stock Units are credited to the Participant's
                  Accounts, provided that for Stock Units credited with respect
                  to the Year ending March 31, 2000, such average daily closing
                  price shall be calculated

                                       5

<PAGE>

                  for the period beginning on January 1, 2000 and ending on such
                  March 31, 2000."

7.    Section 5.04 (c) is hereby amended to be and read as follows:

            "(c)  Dividends. To the extent that a dividend is paid on the
                  Company's common stock, the Committee shall credit to the
                  Accounts of each Participant whose Accounts are invested or
                  deemed invested in Stock Units an amount equal to the value of
                  such dividends. Effective for Plan Years beginning prior to
                  January 1, 2004, such amounts shall be credited to the
                  Participant's Accounts in the form of additional Stock Units
                  at a price equal to one hundred percent (100%) of the closing
                  price on the New York Stock Exchange of a share of the
                  Company's common stock on the date on which such dividend is
                  paid (or if no shares of the Company's common stock are traded
                  on such date, on the immediately preceding trading date).
                  Effective for Plan Years beginning on and after January 1,
                  2004, such amounts shall be credited to the Participant's
                  Accounts in cash."

8.    Section 6.08 is hereby amended to be and read as follows:

      "6.08 Designated Distributions

            Prior to the beginning of a calendar year, a Participant may elect
            that all or any portion of the amount of any Compensation Reduction
            Contribution to be credited to the Participant's Compensation
            Reduction Contribution Account during such calendar year, be
            distributed to or on behalf of the Participant in the form of a lump
            sum in a subsequent calendar year designated by the Participant,
            which subsequent calendar year shall not be earlier than the third
            calendar year following the calendar year for which the election is
            made. Such an election shall be irrevocable. The distribution shall
            be made no later than December 31 of the designated year. In the
            event of the Participant's termination of employment for any reason
            prior to the designated year, the election shall be void and of no
            effect."

                                       6

<PAGE>

      IN WITNESS WHEREOF, the Company has caused this instrument to be executed
in its name and on behalf of this ____day of _______________, 2004, effective as
of January 1, 2004.

                                         TRINITY INDUSTRIES, INC.

                                         By: ___________________________________

                                         Title: ________________________________

ATTEST:

_________________________

STATE OF TEXAS           Section
                         Section
COUNTY OF DALLAS         Section

      This instrument was acknowledged before me on the ___________ day of
______________________________ , 2004, by ______________________________________
of TRINITY INDUSTRIES, INC., a Delaware corporation, on behalf of said
corporation.

                                ________________________________________________
                                Notary Public in and for the
                                State of Texas

My Commission Expires:

_______________________________

                                       7

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