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                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

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

                                  SCHEDULE 13D

             INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT
     TO RULE 13d-1(a) AND AMENDMENTS THERETO FILED PURSUANT TO RULE 13d-2(a)

                                (AMENDMENT NO. 4)


                              PLAINS RESOURCES INC.

                                (Name of Issuer)

 COMMON STOCK, PAR VALUE $.10 PER SHARE               726540503
 --------------------------------------- ---------------------------------------
    (Title of class of securities)                   (CUSIP number)

  JOSEPH A. ORLANDO                  WILLIAM ACKMAN
  LEUCADIA NATIONAL CORPORATION      PERSHING SQUARE CAPITAL MANAGEMENT, LLC
  315 PARK AVENUE SOUTH              110 EAST 42ND STREET
  NEW YORK, NEW YORK 10010           NEW YORK, NEW YORK  10017
  (212) 460-1900                     (212) 813-3700
--------------------------------------------------------------------------------
                  (Name, address and telephone number of person
               authorized to receive notices and communications)

                                 APRIL 19, 2004
--------------------------------------------------------------------------------
             (Date of event which requires filing of this statement)


If the filing person has previously filed a statement on Schedule 13G to report
the acquisition that is the subject of this Schedule 13D, and is filing this
schedule because of Rules 13d-1(e), 13d-1(f) or 13d-1(g), check the following
box [_].


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---------------------------------------------------                              ---------------------------------------------------
CUSIP NO. 726540503                                             13D                                                          PAGE 2
---------------------------------------------------                              ---------------------------------------------------
                                                                                                        
----------------- ----------------------------------------------- ------------------------------------------------------------------
       1          NAME OF REPORTING PERSON:                       Leucadia National Corporation
                  I.R.S. IDENTIFICATION NO. OF ABOVE PERSON (ENTITIES ONLY):
----------------- ------------------------------------------------------------------------------------------------------------------
       2          CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP:                                                     (A) [X]
                                                                                                                        (B) [_]
----------------- ------------------------------------------------------------------------------------------------------------------
       3          SEC USE ONLY

----------------- -------------------------- ---------------------------------------------------------------------------------------
       4          SOURCE OF FUNDS:           NA

----------------- ------------------------------------------------------------------------------------------------------------------
       5          CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
                  PURSUANT TO ITEM 2(d) OR 2(e):                                                                            [_]
----------------- -------------------------------------------------------------- ---------------------------------------------------
       6          CITIZENSHIP OR PLACE OF ORGANIZATION:                          New York

--------------------------- ------ --------------------------------------------- ---------------------------------------------------
        NUMBER OF             7    SOLE VOTING POWER:                            0
          SHARES
                            ------ --------------------------------------------- ---------------------------------------------------
       BENEFICIALLY           8    SHARED VOTING POWER:                          0
         OWNED BY
                            ------ --------------------------------------------- ---------------------------------------------------
           EACH               9    SOLE DISPOSITIVE POWER:                       0
        REPORTING
                            ------ --------------------------------------------- ---------------------------------------------------
       PERSON WITH           10    SHARED DISPOSITIVE POWER:                     0

----------------- ------------------------------------------------------------------------------------------------------------------
       11         AGGREGATE AMOUNT BENEFICIALLY OWNED BY REPORTING PERSON:   0

----------------- ------------------------------------------------------------------------------------------------------------------
       12         CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES:                                    [_]

----------------- ------------------------------------------------------------------------------------------------------------------
       13         PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):   0%

----------------- ----------------------------------------------- ------------------------------------------------------------------
       14         TYPE OF REPORTING PERSON:                       CO

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


                                       2

---------------------------------------------------                              ---------------------------------------------------
CUSIP NO. 726540503                                             13D                                                          PAGE 3
---------------------------------------------------                              ---------------------------------------------------
----------------- ----------------------------------------------- ------------------------------------------------------------------
       1          NAME OF REPORTING PERSON:                                          Pershing Square, L.P.
                  I.R.S. IDENTIFICATION NO. OF ABOVE PERSON (ENTITIES ONLY):             38-3694138
----------------- ------------------------------------------------------------------------------------------------------------------
       2          CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP:                                                    (A) [X]
                                                                                                                       (B) [_]
----------------- ------------------------------------------------------------------------------------------------------------------
       3          SEC USE ONLY

----------------- -------------------------- ---------------------------------------------------------------------------------------
       4          SOURCE OF FUNDS:           NA

----------------- ------------------------------------------------------------------------------------------------------------------
       5          CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
                  PURSUANT TO ITEM 2(d) OR 2(e):                                                                           [_]
----------------- -------------------------------------------------------------- ---------------------------------------------------
       6          CITIZENSHIP OR PLACE OF ORGANIZATION:                          Delaware

--------------------------- ------ --------------------------------------------- ---------------------------------------------------
        NUMBER OF             7    SOLE VOTING POWER:                            0
          SHARES
                            ------ --------------------------------------------- ---------------------------------------------------
       BENEFICIALLY           8    SHARED VOTING POWER:                          1,258,500
         OWNED BY
                            ------ --------------------------------------------- ---------------------------------------------------
           EACH               9    SOLE DISPOSITIVE POWER:                       0
        REPORTING
                            ------ --------------------------------------------- ---------------------------------------------------
       PERSON WITH           10    SHARED DISPOSITIVE POWER:                     1,258,500

----------------- ------------------------------------------------------------------------------------------------------------------
       11         AGGREGATE AMOUNT BENEFICIALLY OWNED BY REPORTING PERSON:   1,258,500

----------------- ------------------------------------------------------------------------------------------------------------------
       12         CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES:                                   [_]

----------------- ------------------------------------------------------------------------------------------------------------------
       13         PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):   5.33%

----------------- ----------------------------------------------- ------------------------------------------------------------------
       14         TYPE OF REPORTING PERSON:                       PN

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


                                       3

---------------------------------------------------                              ---------------------------------------------------
CUSIP NO. 726540503                                             13D                                                          PAGE 4
---------------------------------------------------                              ---------------------------------------------------
----------------- ----------------------------------------------- ------------------------------------------------------------------
       1          NAME OF REPORTING PERSON:                                  Pershing Square GP, LLC
                  I.R.S. IDENTIFICATION NO. OF ABOVE PERSON (ENTITIES ONLY):   38-3694141
----------------- ------------------------------------------------------------------------------------------------------------------
       2          CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP:                                                 (A) [X]
                                                                                                                    (B) [_]
----------------- ------------------------------------------------------------------------------------------------------------------
       3          SEC USE ONLY

----------------- -------------------------- ---------------------------------------------------------------------------------------
       4          SOURCE OF FUNDS:           N/A

----------------- ------------------------------------------------------------------------------------------------------------------
       5          CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
                  PURSUANT TO ITEM 2(d) OR 2(e):                                                                        [_]
----------------- -------------------------------------------------------------- ---------------------------------------------------
       6          CITIZENSHIP OR PLACE OF ORGANIZATION:                          Delaware

--------------------------- ------ --------------------------------------------- ---------------------------------------------------
        NUMBER OF             7    SOLE VOTING POWER:                            0
          SHARES
                            ------ --------------------------------------------- ---------------------------------------------------
       BENEFICIALLY           8    SHARED VOTING POWER:                          1,258,500
         OWNED BY
                            ------ --------------------------------------------- ---------------------------------------------------
           EACH               9    SOLE DISPOSITIVE POWER:                       0
        REPORTING
                            ------ --------------------------------------------- ---------------------------------------------------
       PERSON WITH           10    SHARED DISPOSITIVE POWER:                     1,258,500

----------------- ------------------------------------------------------------------------------------------------------------------
       11         AGGREGATE AMOUNT BENEFICIALLY OWNED BY REPORTING PERSON:   1,258,500
----------------- ------------------------------------------------------------------------------------------------------------------
       12         CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES:                                [_]

----------------- ------------------------------------------------------------------------------------------------------------------
       13         PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):   5.33%

----------------- ----------------------------------------------- ------------------------------------------------------------------
       14         TYPE OF REPORTING PERSON:                       OO

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


                                       4

---------------------------------------------------                              ---------------------------------------------------
CUSIP NO. 726540503                                             13D                                                          PAGE 5
---------------------------------------------------                              ---------------------------------------------------
----------------- ----------------------------------------------- ------------------------------------------------------------------
       1          NAME OF REPORTING PERSON:                                  William Ackman
                  I.R.S. IDENTIFICATION NO. OF ABOVE PERSON (ENTITIES ONLY):
----------------- ------------------------------------------------------------------------------------------------------------------
       2          CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP:                                                   (A) [X]
                                                                                                                      (B) [_]
----------------- ------------------------------------------------------------------------------------------------------------------
       3          SEC USE ONLY

----------------- -------------------------- ---------------------------------------------------------------------------------------
       4          SOURCE OF FUNDS:           N/A

----------------- ------------------------------------------------------------------------------------------------------------------
       5          CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
                  PURSUANT TO ITEM 2(d) OR 2(e):                                                                          [_]
----------------- -------------------------------------------------------------- ---------------------------------------------------
       6          CITIZENSHIP OR PLACE OF ORGANIZATION:                          United States

--------------------------- ------ --------------------------------------------- ---------------------------------------------------
        NUMBER OF             7    SOLE VOTING POWER:                            0
          SHARES
                            ------ --------------------------------------------- ---------------------------------------------------
       BENEFICIALLY           8    SHARED VOTING POWER:                          1,258,500
         OWNED BY
                            ------ --------------------------------------------- ---------------------------------------------------
           EACH               9    SOLE DISPOSITIVE POWER:                       0
        REPORTING
                            ------ --------------------------------------------- ---------------------------------------------------
       PERSON WITH           10    SHARED DISPOSITIVE POWER:                     1,258,500

----------------- ------------------------------------------------------------------------------------------------------------------
       11         AGGREGATE AMOUNT BENEFICIALLY OWNED BY REPORTING PERSON:   1,258,500

----------------- ------------------------------------------------------------------------------------------------------------------
       12         CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES:                                  [_]

----------------- ------------------------------------------------------------------------------------------------------------------
       13         PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):   5.33%

----------------- ----------------------------------------------- ------------------------------------------------------------------
       14         TYPE OF REPORTING PERSON:                       IN

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


                                       5

           This Amendment No. 4, amends the Schedule 13D filed on February 23,
2004, and is filed by Leucadia National Corporation ("Leucadia"), Pershing
Square, L.P., Pershing Square GP, LLC and William Ackman (collectively, the
"Reporting Persons") with respect to the common stock, par value $0.10 per share
("Common Stock"), of Plains Resources Inc. (the "Company").

Item 4.    Purpose of Transaction.
           ----------------------

           Item 4 is hereby supplemented as follows:

           On April 19, 2004, Leucadia sent a letter to the special committee of
the Company's Board of Directors. A copy of the April 19, 2004 letter is
attached hereto as Exhibit 2 and incorporated herein by reference.

Item 7.    Materials to be Filed as Exhibits.
           ---------------------------------

1. Agreement among the Reporting Persons with respect to the filing of this
Schedule 13D.

2. Letter from Leucadia National Corporation to the Special Committee of the
Board of Directors of Plains Resources Inc., dated April 19, 2004.



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                                    SIGNATURE

           After reasonable inquiry and to the best of my knowledge and belief,
I certify that the information set forth in this statement is true, complete and
correct.

                                     LEUCADIA NATIONAL CORPORATION


                                     By:  /s/ Barbara L. Lowenthal
                                        ----------------------------------------
                                         Name:  Barbara L. Lowenthal
                                         Title: Vice President and Comptroller


                                     PERSHING SQUARE, L.P.

                                     By: PERSHING SQUARE GP, LLC


                                     By:  /s/ William Ackman
                                         ---------------------------------------
                                          Name:  William Ackman
                                          Title: Managing Member



                                     PERSHING SQUARE GP, LLC


                                     By:  /s/ William Ackman
                                         ---------------------------------------
                                          Name:  William Ackman
                                          Title: Managing Member



                                     By:  /s/ William Ackman
                                         ---------------------------------------
                                          Name: William Ackman



Date:      April 19, 2004


                                       7

                                  EXHIBIT INDEX
                                  -------------

Exhibit No.
-----------

Exhibit 1 -    Agreement among the Reporting Persons with respect to the filing
               of this Schedule 13D.

Exhibit 2  -   Letter from Leucadia National Corporation to the Special
               Committee of the Board of Directors of Plains Resources Inc.,
               dated April 19, 2004.




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