EXHIBIT 10.65.3

                                December 30, 1999

Via Facsimile

Mr. Alex Cranberg
ASPECT RESOURCES, LLC
511 16th Street, Suite 300
Denver, Colorado  80202
Phone (303) 573-7011
Fax (303) 573-7340

     Re:  Millenium  Joint  Development  Agreement,   Millenium  Project,  dated
          February 10, 1999, as amended (the "Millenium Agreement"); Acquisition
          and Participation  Agreement,  dated October 21, 1999, as amended (the
          "Participation Agreement")

Dear Alex:

         This letter agreement shall set forth the agreement between Brigham Oil
& Gas, L.P.  ("Brigham")  and Aspect  Resources,  LLC  ("Aspect"),  to amend our
Millenium Agreement and Participation Agreement as described below.

         Aspect  hereby  agrees that  notwithstanding  anything to the  contrary
contained in the Millenium Agreement, Brigham shall have until January 31, 2000,
as opposed to December 31, 1999,  to makes its election  under Article II of the
Millenium  Agreement  whether  to  reimburse  Aspect for 75% of all of the costs
which were funded by Aspect and utilized to acquire  Leasehold  Interests during
the second quarter of 1999.


<PAGE>

Aspect Resources, LLC
Letter Agreement
December 30, 1999

Page 2

         Brigham  recognizes that in the event that Brigham does not propose the
drilling  of a  well  within  any  of  the  Prospect  Areas  covered  under  the
Participation Agreement within 30 days from the date hereof, Aspect may exercise
its right to propose a well within any one of such Prospect  Areas.  Anything to
the  contrary  contained  in the  Participation  Agreement,  or the  form  Joint
Operating Agreement attached thereto, notwithstanding,  Brigham and Aspect agree
that in the event that Aspect or any other party  proposes  the  drilling of the
Initial Well within any of the Prospect  Areas and Brigham  desires to elect not
to participate  in the drilling of such Initial Well,  prior to the due date for
its  participation  election,  Brigham  shall  assign to Aspect all of Brigham's
interest in the  applicable  Prospect  Area,  subject to a 35% back-in  interest
after 100% payout of the Initial Well drilled on such Prospect  Area,  being 35%
of the  interest  assigned  by Brigham to Aspect  pursuant  to the terms of this
paragraph,  together  with a like  interest in all wells and all  equipment  and
facilities  related to such wells.  Anything to the  contrary  contained  in the
Participation Agreement, or the form Joint Operating Agreement attached thereto,
notwithstanding,  Brigham and Aspect  agree that in the event that Aspect or any
other  party  proposes  the  drilling  of a  Subsequent  Well  within any of the
Prospect  Areas and Brigham  desires to elect not to participate in the drilling
of such Subsequent Well, prior to the due date for its  participation  election,
Brigham shall assign to Aspect all of Brigham's  interest in the wellbore of the
Subsequent  Well,  subject to a 35%  back-in  interest  after 100% payout of the
Subsequent  Well,  being  35% of the  interest  assigned  by  Brigham  to Aspect
pursuant to the terms of this  paragraph,  together  with a like interest in the
Subsequent Well and all equipment and facilities related to the Subsequent Well.
For purposes of this letter  agreement,  "100%  payout"  shall be deemed to have
occurred at such point in time,  if ever,  that Aspect  (and/or its successor or
assign) has received net  proceeds  attributable  to the interest in the Initial
Well or Subsequent  Well, as the case may be, assigned to Aspect pursuant to the
term hereof,  equaling all of the costs and expenses which have been incurred by
Aspect in the drilling, testing, completing, producing, operating, and reworking
the Initial Well or Subsequent Well, as the case may be.

         All  other  terms  of the  Millenium  Agreement  and the  Participation
Agreement shall continue in full force and effect,  except as expressly modified
by this letter agreement.

         This  letter  agreement  shall be binding  upon and shall  enure to the
benefit of the parties hereto and all of their successors and assigns.

         If  this  letter  agreement   correctly   reflects  the  agreement  and
understanding  of the parties with respect to the subject matter hereof,  we ask
that an authorized representative of Aspect execute a duplicate original or copy
of same and return same to our offices as soon as possible.  Both parties  agree
that the parties may accept  execution and delivery of this letter  agreement by
facsimile  transmission and that either party's execution of a facsimile copy of
this letter agreement shall be an effective execution.

                              Sincerely,
                              BRIGHAM OIL & GAS, L.P.
                              by Brigham, Inc.
                              its Managing General Partner

                              /s/ David T. Brigham

                              David T. Brigham, Vice President


AGREED TO AND ACCEPTED:

ASPECT RESOURCES, LLC
by Aspect Management Corporation
its Manager

By:  /s/ Alex B. Campbell
(name printed) Alex B. Campbell
Its:           Vice President