KEYSPAN CORP
EXHIBIT 10.4-B
<DOCUMENT>
<TYPE>EX-10
<SEQUENCE>5
<FILENAME>ks10k02-exf.txt
<DESCRIPTION>EXHIBIT 10.4-B
<TEXT>
                               EXTENSION AGREEMENT


         This extension agreement (this "Extension") is made as of November 1,
2001, between National Westminster Bank Plc (the "Bank") and KeySpan Generation
LLC (the "Company"), with respect to that certain letter of credit issued by the
Bank in connection with those certain New York State Energy Research and
Development Authority Electric Facilities Revenue Bonds (KeySpan Generation
Project) 1997 Series A (KeySpan Generation Projects) (the "Letter of Credit"),
pursuant to a Letter of Credit and Reimbursement Agreement dated as of December
1, 2000 (the "Agreement") between the Bank and the Company. Capitalized terms
used herein and not otherwise defined shall have the meaning given to them in
the Agreement.

1. Pursuant to Section 2.1(b) of the Agreement, the Company has requested a
waiver of the notice provisions with respect to the extension of the Letter of
Credit and also requested an extension of the Stated Termination Date as of the
date hereof from December 11, 2001 to December 11, 2002, and the Bank, subject
to the execution of this Extension and the terms and conditions hereof, is
willing to so extend the Stated Termination Date pursuant to an amendment of the
Letter of Credit in the form of Exhibit "A" hereto.

2. In connection with such request, the Company agrees to pay to the Bank all
fees and expenses as set forth in Section 2.6 of the Agreement, and to pay to
the Bank on the date hereof a renewal fee of $13,528.00 and allocated internal
costs of $1,000.00.

3. The Company reaffirms each of the representations and warranties contained in
Article 3 of the Agreement under the Agreement as of the date hereof as though
made on the date hereof and reaffirms each of its obligations under the
Agreement.

         In witness whereof, the Company and the Bank have executed this
extension in counterpart copies (all of which shall constitute but one original)
as of the date set forth above.



                                KEYSPAN GENERATION LLC



                                By:  /s/PAUL NICK
                                   -------------------
                                Name: Paul Nick
                                Title: Controller



                                NATIONAL WESTMINSTER BANK PLC NEW YORK BRANCH



                                By: /s/ SCOTT W. BARTON
                                   -------------------------
                                Name: Scott W. Barton
                                Title: Senior Vice President


<PAGE>





                                   EXHIBIT "A"


                          AMENDMENT TO LETTER OF CREDIT

                          IRREVOCABLE LETTER OF CREDIT
                                   NO. NWB2030

                                November 1, 2001




The Chase Manhattan Bank
450 W. 33rd Street - 15th Floor
New York, NY 10001


                  ATTENTION: CAPITAL MARKETS FIDUCIARY SERVICES

Dear Sir or Madam:

At the request of KeySpan Generation LLC, we hereby amend our Irrevocable Letter
of Credit No. NWB2030 by deleting the Stated Termination Date of December 11,
2001 set forth therein and replacing it with December 11, 2002.


Please acknowledge your receipt of and consent to this amendment by executing
the enclosed copy of this amendment and returning it to Ms. Sheila Shaw at the
address set forth above.


Very truly yours,

NATIONAL WESTMINSTER BANK PLC, NEW YORK BRANCH


By: ________________________
         Authorized Officer


By: ________________________
         Authorized Officer


Acknowledge and consented to on November __, 2001:

The Chase Manhattan Bank


By: _________________
Name:
Title:

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</DOCUMENT>
