<PAGE>
                                                                    EXHIBIT 4.34

                                 THIRD AMENDMENT
                             TO REVOLVING CREDIT AND
                               GUARANTY AGREEMENT


                  THIRD AMENDMENT, dated as of December 22, 2003 (the
"Amendment"), to the REVOLVING CREDIT AND GUARANTY AGREEMENT, dated as of
January 31, 2003, among AMERICAN COMMERCIAL LINES LLC, a Delaware limited
liability company (the "Borrower"), a debtor and debtor-in-possession under
Chapter 11 of the Bankruptcy Code, the Guarantors named therein (the
"Guarantors"), JPMORGAN CHASE BANK, a New York banking corporation ("JPMorgan
Chase"), each of the other financial institutions from time to time party
thereto (the "Lenders"), and JPMORGAN CHASE BANK, as Administrative Agent for
the Lenders (in such capacity, the "Agent"), and BANK ONE, N.A. and GENERAL
ELECTRIC CAPITAL CORPORATION, as Co-Syndication Agents (in such capacities, the
"Co-Syndication Agents"):

                              W I T N E S S E T H:

                  WHEREAS, the Borrower, the Guarantors, the Lenders, the Agent
and the Co-Syndication Agents are parties to that certain Revolving Credit and
Guaranty Agreement, dated as of January 31, 2003, as amended by that certain
First Amendment to Revolving Credit and Guaranty Agreement, dated as of March
13, 2003, and that Second Amendment to Revolving Credit and Guaranty Agreement,
dated as of March 31, 2003 (as the same may be further amended, modified or
supplemented from time to time, the "Credit Agreement"); and

                  WHEREAS, the Borrower, the Guarantors and the Lenders have
agreed to amend certain provisions of the Credit Agreement as set forth herein,
subject to the terms and conditions set forth herein; and

                  NOW, THEREFORE, it is agreed as follows:

                  As used herein, all terms that are defined in the Credit
Agreement shall have the same meanings herein.

                  1.       Amendments. The Credit Agreement is hereby amended as
follows:

         (a)               Section 6.10 of the Credit Agreement is amended by
adding the following parenthetical clause at the end of subsection (iii)
thereof:

                  (provided, further, that, during the period beginning December
                  22, 2003 and ending on March 15, 2004, the aggregate
                  outstanding principal amount of such advances and loans to
                  Jeffboat LLC may not exceed $4,000,000),
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                  2.       Miscellaneous.

                  This Amendment shall not become effective until the date on
which this Amendment shall have been executed by the Borrower, the Guarantors
and the Required Lenders, and the Agent shall have received evidence
satisfactory to it of such execution (the "Effective Date").

                  Except to the extent hereby amended, the Credit Agreement and
each of the Loan Documents remain in full force and effect and are hereby
ratified and affirmed.

                  The Borrower agrees that its obligations set forth in Section
10.05 of the Credit Agreement shall extend to the preparation, execution and
delivery of this Amendment, including the reasonable fees and disbursements of
special counsel to the Agent.

                  This Amendment shall be limited precisely as written and shall
not be deemed (a) to be a consent granted pursuant to, or a waiver or
modification of, any other term or condition of the Credit Agreement or any of
the instruments or agreements referred to therein or (b) to prejudice any right
or rights which the Agent, the Co-Syndication Agents or the Lenders may now have
or have in the future under or in connection with the Credit Agreement or any of
the instruments or agreements referred to therein. Whenever the Credit Agreement
is referred to in the Credit Agreement or any of the instruments, agreements or
other documents or papers executed or delivered in connection therewith, such
reference shall be deemed to mean the Credit Agreement as modified by this
Amendment.

                  This Amendment may be executed in any number of counterparts
and by the different parties hereto in separate counterparts, each of which when
so executed and delivered shall be deemed to be an original and all of which
taken together shall constitute but one and the same instrument.

                  This Amendment shall be governed by, and construed in
accordance with, the laws of the State of New York.


                           [SIGNATURE PAGES TO FOLLOW]


                                       2
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                  IN WITNESS WHEREOF, the parties hereto have caused this
Amendment to be duly executed as of the day and the year first written.

                                     BORROWER:

                                     AMERICAN COMMERCIAL LINES LLC


                                     By:
                                            -------------------------------
                                     Title:


                                     GUARANTORS:

                                     AMERICAN COMMERCIAL LINES HOLDINGS LLC


                                     By:
                                            -------------------------------
                                     Title:


                                     LOUISIANA DOCK COMPANY LLC


                                     By:
                                            -------------------------------
                                     Title:


                                     AMERICAN COMMERCIAL TERMINALS LLC


                                     By:
                                            -------------------------------
                                     Title:


                                     JEFFBOAT LLC


                                     By:
                                            -------------------------------
                                     Title:


                                     ACL CAPITAL CORP.


                                     By:
                                            -------------------------------
                                     Title:
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                                     AMERICAN COMMERCIAL BARGE LINE LLC


                                     By:
                                            -------------------------------
                                     Title:


                                     AMERICAN COMMERCIAL LINES INTERNATIONAL LLC


                                     By:
                                            -------------------------------
                                     Title:


                                     ACBL LIQUID SALES LLC


                                     By:
                                            -------------------------------
                                     Title:


                                     AMERICAN COMMERCIAL LOGISTICS LLC


                                     By:
                                            -------------------------------
                                     Title:


                                     HOUSTON FLEET LLC


                                     By:
                                            -------------------------------
                                     Title:


                                     LEMONT HARBOR & FLEETING SERVICES LLC


                                     By:
                                            -------------------------------
                                     Title:


                                     AMERICAN COMMERCIAL TERMINALS - MEMPHIS LLC


                                     By:
                                            -------------------------------
                                     Title:
<PAGE>
                                     ORINOCO TASA LLC


                                     By:
                                            -------------------------------
                                     Title:


                                     ORINOCO TASV LLC


                                     By:
                                            -------------------------------
                                     Title:
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                                     LENDERS:



                                     -------------------------------
                                     NAME OF INSTITUTION



                                     By:
                                            -------------------------------
                                     Title: