Ameren Corp

July 12, 2004 David A. Whiteley

Exhibit 10.3

          July 12, 2004



          David A. Whiteley
          Senior Vice President
          AmerenCILCO
          1901 Chouteau Avenue
          St. Louis, MO 63103

          Re: Extension of AmerenCILCO-AERG Power Supply Agreement


[GRAPHIC OMITTED]


          Dear Mr. Whiteley:

          This will confirm that  AmerenCILCO and AERG have agreed to extend the
          term of their Power Supply Agreement (PSA) through December 31, 2006.

          We take this action  pursuant  to Section 2.2 of the PSA which  allows
          for it to be extended  beyond the Initial Term  (December 31, 2004) by
          the mutual  written  agreement  of the parties.  As a result,  the PSA
          shall be extended beyond the Initial Term through December 31, 2006.

          Our signatures below confirm our agreement.

          Yours very truly,

          /s/ Thomas R. Voss
          Thomas R. Voss
          President
          AmerenEnergy Resources Generating Company


          Agreed:


          /s/ David A. Whiteley

          -----------------------------
          David A. Whiteley
          Senior Vice President
          AmerenCILCO