UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D. C. 20549


                                    FORM 10-Q


                Quarterly Report Pursuant to Section 13 or 15(d)
                     of the Securities Exchange Act of 1934


                For the quarterly period ended September 30, 2001


                         Commission File No. 33-26097-08


                        PARKER & PARSLEY 90-B CONV., L.P.
                       -----------------------------------
             (Exact name of Registrant as specified in its charter)


                    Delaware                                75-2329284
    ----------------------------------------           ---------------------
        (State or other jurisdiction of                   (I.R.S. Employer
         incorporation or organization)                Identification Number)


5205 N. O'Connor Blvd., Suite 1400, Irving, Texas               75039
-------------------------------------------------           ------------
   (Address of principal executive offices)                  (Zip code)

       Registrant's Telephone Number, including area code : (972) 444-9001


          Not applicable (Former name, former address and former fiscal
                       year, if changed since last report)

Indicate by check mark whether the Registrant (1) has filed all reports required
to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during
the  preceding 12 months (or for such  shorter  period that the  Registrant  was
required  to file  such  reports),  and  (2) has  been  subject  to such  filing
requirements for the past 90 days.

                                Yes / x / No / /





<PAGE>



                        PARKER & PARSLEY 90-B CONV., L.P.

                                TABLE OF CONTENTS


                                                                        Page
                          Part I. Financial Information

Item 1.     Financial Statements

            Balance Sheets as of September 30, 2001 and
               December 31, 2000......................................    3

            Statements of Operations for the three and nine
              months ended September 30, 2001 and 2000................    4

            Statement of Partners' Capital for the nine months
              ended September 30, 2001................................    5

            Statements of Cash Flows for the nine months ended
              September 30, 2001 and 2000.............................    6

            Notes to Financial Statements.............................    7

Item 2.     Management's Discussion and Analysis of Financial
              Condition and Results of Operations.....................    8


                           Part II. Other Information

Item 6.     Exhibits and Reports on Form 8-K..........................   12

            Signatures................................................   13



                                        2

<PAGE>



                        PARKER & PARSLEY 90-B CONV., L.P.
                        (A Delaware Limited Partnership)

                          Part I. Financial Information

Item 1.     Financial Statements

                                 BALANCE SHEETS
<TABLE>

                                                   September 30,  December 31,
                                                       2001           2000
                                                   ------------   -----------
                                                   (Unaudited)
                 ASSETS
<S>                                                <C>            <C>
Current assets:
  Cash                                             $   292,511    $   132,300
  Accounts receivable - oil and gas sales              144,371        209,552
                                                    ----------     ----------
           Total current assets                        436,882        341,852
                                                    ----------     ----------
Oil and gas properties - at cost,  based on the
  successful efforts accounting method               9,567,572      9,628,120
Accumulated depletion                               (8,108,789)    (8,075,752)
                                                    ----------     ----------
           Net oil and gas properties                1,458,783      1,552,368
                                                    ----------     ----------
                                                   $ 1,895,665    $ 1,894,220
                                                    ==========     ==========
LIABILITIES AND PARTNERS' CAPITAL

Current liabilities:
  Accounts payable - affiliate                     $    50,571    $    15,580

Partners' capital:
  Managing general partner                              18,450         18,785
  Limited partners (11,897 interests)                1,826,644      1,859,855
                                                    ----------     ----------
                                                     1,845,094      1,878,640
                                                    ----------     ----------
                                                   $ 1,895,665    $ 1,894,220
                                                    ==========     ==========

</TABLE>


The financial information included as of September 30, 2001 has been prepared by
  the managing general partner without audit by independent public accountants.

   The accompanying notes are an integral part of these financial statements.

                                        3

<PAGE>



                        PARKER & PARSLEY 90-B CONV., L.P.
                        (A Delaware Limited Partnership)

                            STATEMENTS OF OPERATIONS
                                   (Unaudited)



<TABLE>

                                           Three months ended         Nine months ended
                                              September 30,              September 30,
                                        ------------------------    ------------------------
                                           2001          2000          2001          2000
                                        ----------    ----------    ----------    ----------
<S>                                     <C>           <C>           <C>           <C>
Revenues:
  Oil and gas                           $  300,263    $  405,161    $1,063,346    $1,092,350
  Interest                                   1,957         3,426         7,043         8,203
  Gain on disposition of assets              4,410           -           7,464         2,023
                                         ---------     ---------     ---------     ---------
                                           306,630       408,587     1,077,853     1,102,576
                                         ---------     ---------     ---------     ---------
Costs and expenses:
  Oil and gas production                   168,131       135,775       450,324       413,083
  General and administrative                 8,287        13,970        31,171        35,694
  Impairment of oil and gas properties      11,272           -          11,272           -
  Depletion                                 31,450        24,992        85,849        77,504
  Abandoned property                            79           -           3,138           -
                                         ---------     ---------     ---------     ---------
                                           219,219       174,737       581,754       526,281
                                         ---------     ---------     ---------     ---------
Net income                              $   87,411    $  233,850    $  496,099    $  576,295
                                         =========     =========     =========     =========
Allocation of net income:
  Managing general partner              $      874    $    2,339    $    4,961    $    5,763
                                         =========     =========     =========     =========
  Limited partners                      $   86,537    $  231,511    $  491,138    $  570,532
                                         =========     =========     =========     =========
Net income per limited
  partnership interest                  $     7.27    $    19.46    $    41.28    $    47.96
                                         =========     =========     =========     =========

</TABLE>


         The financial information included herein has been prepared by
  the managing general partner without audit by independent public accountants.

   The accompanying notes are an integral part of these financial statements.

                                        4

<PAGE>



                        PARKER & PARSLEY 90-B CONV., L.P.
                        (A Delaware Limited Partnership)

                         STATEMENT OF PARTNERS' CAPITAL
                                   (Unaudited)



<TABLE>

                                         Managing
                                         general       Limited
                                         partner       partners       Total
                                        ----------    ----------    ----------


<S>                                     <C>           <C>           <C>
Balance at January 1, 2001              $   18,785    $1,859,855    $1,878,640

    Distributions                           (5,296)     (524,349)     (529,645)

    Net income                               4,961       491,138       496,099
                                         ---------     ---------     ---------

Balance at September 30, 2001           $   18,450    $1,826,644    $1,845,094
                                         =========     =========     =========

</TABLE>



         The financial information included herein has been prepared by
  the managing general partner without audit by independent public accountants.

   The accompanying notes are an integral part of these financial statements.

                                        5

<PAGE>



                        PARKER & PARSLEY 90-B CONV., L.P.
                        (A Delaware Limited Partnership)

                            STATEMENTS OF CASH FLOWS
                                   (Unaudited)


<TABLE>

                                                           Nine months ended
                                                              September 30,
                                                       ------------------------
                                                           2001         2000
                                                       ----------    ----------
<S>                                                    <C>           <C>
Cash flows from operating activities:
   Net income                                          $  496,099    $  576,295
   Adjustments to reconcile net income to net
      cash provided by operating activities:
        Impairment of oil and gas properties               11,272           -
        Depletion                                          85,849        77,504
        Gain on disposition of assets                      (7,464)       (2,023)
   Changes in assets and liabilities:
        Accounts receivable                                65,181       (47,783)
        Accounts payable                                   34,991        19,871
                                                        ---------     ---------
          Net cash provided by operating activities       685,928       623,864
                                                        ---------     ---------
Cash flows from investing activities:
   Additions to oil and gas properties                     (3,650)      (14,214)
   Proceeds from asset dispositions                         7,578         2,023
                                                        ---------     ---------
          Net cash provided by (used in) investing
            activities                                      3,928       (12,191)
                                                        ---------     ---------
Cash flows used in financing activities:
   Cash distributions to partners                        (529,645)     (597,062)
                                                        ---------     ---------
Net increase in cash                                      160,211        14,611
Cash at beginning of period                               132,300       132,031
                                                        ---------     ---------
Cash at end of period                                  $  292,511    $  146,642
                                                        =========     =========
</TABLE>




         The financial information included herein has been prepared by
  the managing general partner without audit by independent public accountants.

   The accompanying notes are an integral part of these financial statements.

                                        6

<PAGE>



                        PARKER & PARSLEY 90-B CONV., L.P.
                        (A Delaware Limited Partnership)

                          NOTES TO FINANCIAL STATEMENTS
                               September 30, 2001
                                   (Unaudited)


Note 1.     Organization and nature of operations

Parker & Parsley 90-B Conv., L.P. (the "Partnership") was organized as a general
partnership  in 1990 under the laws of the State of Texas and was converted to a
Delaware limited partnership on August 1, 1991.

The  Partnership  engages in oil and gas development and production in Texas and
is not involved in any industry segment other than oil and gas.

Note 2.     Basis of presentation

In  the  opinion  of  management,  the  unaudited  financial  statements  of the
Partnership  as of  September  30, 2001 and for the three and nine months  ended
September 30, 2001 and 2000 include all adjustments and accruals consisting only
of  normal  recurring  accrual  adjustments  which  are  necessary  for  a  fair
presentation  of the results for the interim  period.  These interim results are
not necessarily indicative of results for a full year. Certain reclassifications
may have been made to the September 30, 2000 financial  statements to conform to
the September 30, 2001 financial statement presentations.

Certain  information  and footnote  disclosures  normally  included in financial
statements prepared in accordance with generally accepted accounting  principles
have been  condensed  or omitted in this Form 10-Q  pursuant  to the results and
regulations of the Securities and Exchange Commission.  The financial statements
should  be read in  conjunction  with the  financial  statements  and the  notes
thereto  contained in the  Partnership's  Report on Form 10-K for the year ended
December 31, 2000, as filed with the Securities and Exchange Commission,  a copy
of which is available upon request by writing to Rich Dealy,  Vice President and
Chief Accounting  Officer,  5205 North O'Connor  Boulevard,  Suite 1400, Irving,
Texas 75039-3746.

Note 3.     Impairment of long-lived assets

In  accordance  with  Statement  of  Financial  Accounting  Standards  No.  121,
"Accounting for the Impairment of Long-Lived Assets and for Long-Lived Assets to
be Disposed Of" ("SFAS  121"),  the  Partnership  reviews its proved oil and gas
properties for impairment  whenever events and circumstances  indicate a decline
in the  recoverability  of the carrying value of the  Partnership's  oil and gas
properties.  The Partnership has estimated the expected future cash flows of its
oil and gas properties as of September 30, 2001, based on proved  reserves,  and
compared such estimated  future cash flows to the respective  carrying amount of
the oil and gas  properties to determine if the carrying  amounts were likely to
be  recoverable.  For those proved oil and gas properties for which the carrying
amount exceeded the estimated future cash flows, an impairment was determined to


                                        7

<PAGE>



exist; therefore,  the Partnership adjusted the carrying amount of those oil and
gas properties to their fair value as determined by  discounting  their expected
future cash flows at a discount rate commensurate with the risks involved in the
industry.  As  a  result,  the  Partnership  recognized  a  non-cash  impairment
provision  of $11,272  related to its proved oil and gas  properties  during the
nine months ended September 30, 2001.

Note 4.     Proposal to acquire Partnership

On October 22,  2001,  Pioneer  Natural  Resources  Company  ("Pioneer")  mailed
definitive materials (the "proxy  statement/prospectus") to solicit the approval
of the limited partners of the  Partnership.  Pioneer has valued the Partnership
interest at  $3,275,273 of which  $3,220,716 is allocated to the  non-affiliated
limited partners. If a majority of the limited partners approve the transaction,
the limited  partners  will  receive  their value in the form of Pioneer  common
stock.

Item 2.     Management's Discussion and Analysis of Financial Condition
              and Results of Operations (1)

Results of Operations

Nine months ended September 30, 2001 compared with nine months ended September
   30, 2000

Revenues:

The Partnership's  oil and gas revenues  decreased 3% to $1,063,346 for the nine
months ended September 30, 2001 as compared to $1,092,350 for the same period in
2000. The decrease in revenues  resulted from lower average prices  received for
oil and natural  gas liquids  ("NGLs")  and a decline in  production,  offset by
higher average prices  received for gas. For the nine months ended September 30,
2001,  25,759 barrels of oil,  10,283 barrels of NGLs and 51,734 mcf of gas were
sold, or 44,664 barrel of oil  equivalents  ("BOEs").  For the nine months ended
September 30, 2000, 27,178 barrels of oil, 12,971 barrels of NGLs and 50,036 mcf
of gas were sold,  or 48,488  BOEs.  Due to the decline  characteristics  of the
Partnership's  oil and gas  properties,  management  expects a certain amount of
decline  in  production  in the  future  until  the  Partnership's  economically
recoverable reserves are fully depleted.

The average price received per barrel of oil decreased $1.07, or 4%, from $28.68
for the nine months  ended  September  30, 2000 to $27.61 for the same period in
2001. The average price received per barrel of NGLs decreased  $.33, or 2%, from
$14.66  during the nine months ended  September  30, 2000 to $14.33 for the same
period in 2001.  The average  price  received per mcf of gas  increased 62% from
$2.45 for the nine months ended  September 30, 2000 to $3.96 for the same period
in 2001.  The market  price for oil and gas has been  extremely  volatile in the
past decade and management expects a certain amount of volatility to continue in
the  foreseeable  future.  The Partnership may therefore sell its future oil and
gas production at average  prices lower or higher than that received  during the
nine months ended September 30, 2001.

Gains on disposition of assets of $7,464 and $2,023 were  recognized  during the
nine months ended September 30, 2001 and 2000, respectively. The gain recognized
during the period  ended September 30,  2001 consisted of  $7,033 salvage income

                                        8

<PAGE>



from  one well  plugged  and  abandoned  in the  current  period  and $431  from
equipment  credits  received on one fully  depleted  well.  The gain  recognized
during the period ended  September  30, 2000 was due to the sale of equipment on
one fully depleted well. Abandoned property costs of $3,138 were incurred during
the nine months ended September 30, 2001 to plug one well in the current period.

Costs and Expenses:

Total  costs and  expenses  increased  to  $581,754  for the nine  months  ended
September  30,  2001 as compared  to  $526,281  for the same period in 2000,  an
increase of $55,473,  or 11%. The  increase  was due to increases in  production
costs,  the  impairment  of oil  and gas  properties,  depletion  and  abandoned
property  costs,  offset by a decline in  general  and  administrative  expenses
("G&A").

Production  costs were $450,324 for the nine months ended September 30, 2001 and
$413,083 for the same period in 2000,  resulting in a $37,241  increase,  or 9%.
The  increase  was  primarily  due to higher  ad  valorem  taxes and  additional
workover and well maintenance costs incurred to stimulate well production.

G&A's  components are independent  accounting and engineering  fees and managing
general partner personnel and operating costs. During this period, G&A decreased
13% from $35,694 for the nine months ended September 30, 2000 to $31,171 for the
same period in 2001, primarily due to a lower percentage of the managing general
partner's  G&A being  allocated  (limited  to 3% of oil and gas  revenues)  as a
result of decreased oil and gas revenues.

In  accordance  with  Statement  of  Financial  Accounting  Standards  No.  121,
"Accounting for the Impairment of Long-Lived Assets and for Long-Lived Assets to
be Disposed Of" ("SFAS  121"),  the  Partnership  reviews its proved oil and gas
properties for impairment  whenever events and circumstances  indicate a decline
in the  recoverability  of the carrying value of the  Partnership's  oil and gas
properties.  The Partnership has estimated the expected future cash flows of its
oil and gas properties as of September 30, 2001, based on proved  reserves,  and
compared such estimated  future cash flows to the respective  carrying amount of
the oil and gas  properties to determine if the carrying  amounts were likely to
be  recoverable.  For those proved oil and gas properties for which the carrying
amount exceeded the estimated future cash flows, an impairment was determined to
exist; therefore,  the Partnership adjusted the carrying amount of those oil and
gas properties to their fair value as determined by  discounting  their expected
future cash flows at a discount rate commensurate with the risks involved in the
industry.  As  a  result,  the  Partnership  recognized  a  non-cash  impairment
provision  of $11,272  related to its proved oil and gas  properties  during the
nine months ended September 30, 2001.

Depletion  was $85,849 for the nine months ended  September 30, 2001 as compared
to $77,504 for the same period in 2000,  representing an increase of $8,345,  or
11%. This increase was  primarily due to a reduction in proved  reserves  during
the period ended September 30, 2001 due to lower commodity prices as compared to
the  same  period  in 2000,  offset  by a  reduction  in the  Partnership's  net
depletable  basis  from  charges  taken in  accordance  with SFAS 121 during the
fourth quarter of 2000 and a decrease in oil production of 1,419 barrels for the
nine months ended September 30, 2001 as compared to the same period in 2000.

                                        9

<PAGE>



Three months ended September 30, 2001 compared with three months ended September
   30, 2000

Revenues:

The Partnership's  oil and gas revenues  decreased 26% to $300,263 for the three
months ended  September  30, 2001 as compared to $405,161 for the same period in
2000. The decrease in revenues resulted from lower average prices received and a
decline in  production.  For the three months ended  September  30, 2001,  8,406
barrels of oil, 3,873 barrels of NGLs and 16,365 mcf of gas were sold, or 15,007
BOEs. For the three months ended September 30, 2000, 9,220 barrels of oil, 4,367
barrels  of NGLs and 17,020 mcf of gas were  sold,  or 16,424  BOEs.  Due to the
decline characteristics of the Partnership's oil and gas properties,  management
expects a certain  amount of  decline  in  production  in the  future  until the
Partnership's economically recoverable reserves are fully depleted.

The average  price  received per barrel of oil  decreased  $4.26,  or 14%,  from
$30.54  during the three months ended  September 30, 2000 to $26.28 for the same
period in 2001. The average price  received per barrel of NGLs decreased  $4.53,
or 28%, from $15.94  during the three months ended  September 30, 2000 to $11.41
for the same period in 2001. The average price received per mcf of gas decreased
32% from $3.17 during the three months ended September 30, 2000 to $2.16 for the
same period in 2001.

A gain on  disposition  of assets of $4,410  recognized  during the three months
ended  September 30, 2001 was due to $3,979 salvage income from one well plugged
and abandoned in the current period and $431 from equipment  credits received on
one fully depleted well.  Abandoned  property costs of $79 were incurred  during
the three months ended September 30, 2001 to plug this well.

Costs and Expenses:

Total costs and  expenses  increased  to  $219,219  for the three  months  ended
September  30,  2001 as compared  to  $174,737  for the same period in 2000,  an
increase of $44,482,  or 25%.  This  increase was due to increases in production
costs,  the  impairment  of oil  and gas  properties,  depletion  and  abandoned
property costs, offset by a decline in G&A.

Production costs were $168,131 for the three months ended September 30, 2001 and
$135,775 for the same period in 2000,  resulting in a $32,356 increase,  or 24%.
The  increase  was  primarily  due to higher  ad  valorem  taxes and  additional
workover  and well  maintenance  costs  incurred to stimulate  well  production,
offset by a decrease in production taxes.

During this period,  G&A  decreased  41% from $13,970 for the three months ended
September  30,  2000 to $8,287 for the same period in 2001,  primarily  due to a
lower percentage of the managing general partner's G&A being allocated  (limited
to 3% of oil and gas revenues) as a result of decreased oil and gas revenues.

The Partnership recognized a non-cash impairment provision of $11,272 related to
its proved oil and gas  properties  during the three months ended  September 30,
2001.

                                       10

<PAGE>




Depletion was $31,450 for the three months ended  September 30, 2001 as compared
to $24,992 for the same period in 2000,  representing an increase of $6,458,  or
26%. This increase was attributable to a reduction in proved reserves during the
period  ended  September  30,  2001 as a result  of lower  commodity  prices  as
compared to the same period in 2000,  offset by a reduction in the Partnership's
net depletable  basis from charges taken in accordance  with SFAS 121 during the
fourth  quarter of 2000 and a decrease in oil  production of 814 barrels for the
three months ended September 30, 2001 as compared to the same period in 2000.

Liquidity and Capital Resources

Net Cash Provided by Operating Activities

Net cash  provided by operating  activities  increased  $62,064  during the nine
months ended  September 30, 2001 from the same period ended  September 30, 2000.
This increase was due to reductions of $128,084 in working capital and $4,523 in
G&A expenses,  offset by increases of $37,241 in production  costs and $3,138 in
abandoned property costs and a decline in oil and gas sales receipts of $30,164.
The  decrease in oil and gas receipts  resulted  from the decline in oil and NGL
prices during 2001 which  resulted in a $33,470  decline to oil and gas receipts
and $70,974  resulting from the decline in production during 2001 as compared to
the same period in 2000,  offset by an increase in gas prices which  contributed
an additional $74,280 to oil and gas receipts.  The increase in production costs
was primarily due to higher ad valorem  taxes and  additional  workover and well
maintenance costs incurred to stimulate well production. The decrease in G&A was
primarily due to a lower percentage of the managing general  partner's G&A being
allocated  (limited to 3% of oil and gas  revenues) as a result of decreased oil
and gas revenues.

Net Cash Provided by (Used in) Investing Activities

The  Partnership's  investing  activities during the nine months ended September
30, 2001 and 2000 included expenditures related to equipment upgrades on various
oil and gas properties.

Proceeds from asset dispositions of $7,578 and $2,023 were recognized during the
nine months  ended  September  30,  2001 and 2000,  respectively.  The  proceeds
recognized  during the period ended  September  30, 2001 were  primarily  due to
salvage  income from one well plugged and abandoned  during the current  period.
The proceeds  recognized during the period ended September 30, 2000 were derived
from the sale of equipment on one fully depleted well.

Net Cash Used in Financing Activities

For the nine months ended September 30, 2001, cash distributions to the partners
were $529,645,  of which $5,296 was distributed to the managing  general partner
and $524,349 to the limited  partners.  For the same period ended  September 30,
2000,  cash  distributions  to the partners were  $597,062,  of which $5,971 was
distributed  to the  managing  general  partner  and  $591,091  to  the  limited
partners.

During  2001,  the  Partnership  made  distributions  in  March  and July but no
distributions  were made by the Partnership during September pending the vote of


                                       11

<PAGE>



the proposed merger of the Partnership into Pioneer Natural  Resources USA, Inc.
("Pioneer USA"). For further information, see "Proposal to acquire partnerships"
below.

Proposal to acquire partnerships

On October 22,  2001,  Pioneer  Natural  Resources  Company  ("Pioneer")  mailed
definitive materials (the "proxy  statement/prospectus") to solicit the approval
of limited partners of 46 Parker & Parsley limited  partnerships,  including the
Partnership,  of an agreement and plan of merger among  Pioneer,  Pioneer USA, a
wholly-owned subsidiary of Pioneer, and those limited partnerships.  The special
meetings of the limited partners to consider and vote on the merger proposal are
scheduled  for  December  20,  2001.  The record  date to  identify  the limited
partners who are  entitled to notice of and to vote at the special  meetings was
September  21, 2001.  Each  partnership  that approves the agreement and plan of
merger and the other related  merger  proposals will merge with and into Pioneer
USA.  As a result,  the  partnership  interests  of those  partnerships  will be
converted into the right to receive Pioneer common stock.

The proxy  statement/prospectus  is  non-binding  and is subject to, among other
things,  consideration  of offers from third parties to purchase any partnership
or its assets and the majority approval of the limited partnership  interests in
each partnership.

A copy of the proxy  statement/prospectus  may be obtained  without  charge upon
request from Pioneer Natural Resources Company, 5205 North O'Connor Blvd., Suite
1400, Irving, Texas 75039, Attention: Investor Relations.

The limited partners are urged to read the proxy statement/prospectus of Pioneer
filed with the Securities and Exchange  Commission because it contains important
information about the proposed mergers,  including  information about the direct
and indirect  interests  of Pioneer USA and Pioneer in the mergers.  The limited
partners may also obtain the final proxy statement/prospectus and other relevant
documents  relating to the  proposed  mergers free through the internet web site
that the Securities and Exchange Commission maintains at www.sec.gov.

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

(1)  "Item 2.  Management's  Discussion and Analysis of Financial  Condition and
     Results of Operations"  contains  forward  looking  statements that involve
     risks and uncertainties.  Accordingly,  no assurances can be given that the
     actual  events  and  results  will  not be  materially  different  than the
     anticipated results described in the forward looking statements.


                           Part II. Other Information

Item 6.     Exhibits and Reports on Form 8-K

(a)    Exhibits

(b)    Reports on Form 8-K - none

                                       12

<PAGE>


                        PARKER & PARSLEY 90-B CONV., L.P.
                        (A Delaware Limited Partnership)



                               S I G N A T U R E S



       Pursuant to the requirements of the Securities Exchange Act of 1934,  the
Registrant  has duly  caused  this  report  to be  signed  on its  behalf by the
undersigned thereunto duly authorized.


                                           PARKER & PARSLEY 90-B CONV., L.P.

                                  By:      Pioneer Natural Resources USA, Inc.,
                                             Managing General Partner




Dated:  November 7, 2001         By:      /s/ Rich Dealy
                                           ----------------------------------
                                           Rich Dealy, Vice President and
                                             Chief Accounting Officer



                                       13

<PAGE>