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                                      Filed by Pioneer Natural Resources Company
                           Pursuant to Rule 425 under the Securities Act of 1933
                                                Subject Company:  See List Below
                                                   Commission File No. 333-59094

Company

                                                        
Parker & Parsley 81-I, Ltd.                                Parker & Parsley 88-A Conv., L.P.
Parker & Parsley 81-II, Ltd.                               Parker & Parsley 88-A, L.P.
Parker & Parsley 82-I, Ltd.                                Parker & Parsley 88-B Conv., L.P.
Parker & Parsley 82-II, Ltd.                               Parker & Parsley 88-B, L.P.
Parker & Parsley 82-III, Ltd.                              Parker & Parsley 88-C Conv., L.P.
Parker & Parsley 83-A, Ltd.                                Parker & Parsley 88-C, L.P.
Parker & Parsley 83-B, Ltd.                                Parker & Parsley Producing Properties 88-A, L.P.
Parker & Parsley 84-A, Ltd.                                Parker & Parsley Private Investment 88, L.P.
Parker & Parsley 85-A, Ltd.                                Parker & Parsley 89-A Conv., L.P.
Parker & Parsley 85-B, Ltd.                                Parker & Parsley 89-A, L.P.
Parker & Parsley Private Investment 85-A, Ltd.             Parker & Parsley 89-B Conv., L.P.
Parker & Parsley Selected 85 Private Investment, Ltd.      Parker & Parsley 89-B, L.P.
Parker & Parsley 86-A, Ltd.                                Parker & Parsley Private Investment 89, L.P.
Parker & Parsley 86-B, Ltd.                                Parker & Parsley 90-A Conv., L.P.
Parker & Parsley 86-C, Ltd.                                Parker & Parsley 90-A, L.P.
Parker & Parsley Private Investment 86, Ltd.               Parker & Parsley 90-B Conv., L.P.
Parker & Parsley 87-A Conv., Ltd.                          Parker & Parsley 90-B, L.P.
Parker & Parsley 87-A, Ltd.                                Parker & Parsley 90-C Conv., L.P.
Parker & Parsley 87-B Conv., Ltd.                          Parker & Parsley 90-C, L.P.
Parker & Parsley 87-B, Ltd.                                Parker & Parsley Private Investment 90, L.P.
Parker & Parsley Producing Properties 87-A, Ltd.           Parker & Parsley 90 Spraberry Private Development, L.P.
Parker & Parsley Producing Properties 87-B, Ltd.           Parker & Parsley 91-A, L.P.
Parker & Parsley Private Investment 87, Ltd.               Parker & Parsley 91-B, L.P.



[PIONEER NATURAL RESOURCES LOGO]

     NEWS RELEASE
- --------------------------------------------------------------------------------
          INVESTOR RELATIONS CONTACT: SUSAN SPRATLEN (972) 444-9001

                PIONEER ENHANCES PROPOSAL TO ACQUIRE PARTNERSHIPS

DALLAS, TEXAS, JUNE 29, 2001 - PIONEER NATURAL RESOURCES COMPANY ("PIONEER")
(NYSE:PXD) (TSE:PXD) announces that it has filed an amendment to its
registration statement filed April 17, 2001 with the Securities and Exchange
Commission ("SEC") (SEC File Number 333-59094) that proposes an agreement and
plan of merger among Pioneer, Pioneer Natural Resources USA, Inc. ("Pioneer
USA"), a wholly-owned subsidiary of Pioneer, and 46 Parker & Parsley limited
partnerships. The amended registration statement reflects an increase in the
price

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offered to limited partners and a change in the form of payment from a
combination of stock and cash to all stock. As previously announced, each
partnership that approves the proposals will merge with and into Pioneer USA.

Pioneer has increased its offer to the unaffiliated limited partners by $10
million to approximately $112 million. Under the revised proposal, the
partnership interests of each such partnership will be converted into the right
to receive Pioneer common stock. The number of shares of Pioneer common stock to
be offered will be based on its average closing price for the ten trading days
ending three trading days before the date of the special meeting of limited
partners to be held later this year. As outlined in the amended registration
statement, the amount Pioneer will pay for the partnership interests will be
based on the partnerships' reserves values and net working capital as of March
31, 2001 less the partnerships' pro rata share of estimated expenses of the
mergers and less subsequent cash distributions to the partners. The reserves
values have been derived from the present value of estimated future net revenues
from the partnerships' oil and natural gas reserves at March 31, 2001, based on
average NYMEX long-term oil and natural gas prices. Pioneer will include in its
offer the partnerships' undistributed net working capital as of March 31, 2001.
Related merger expenses will be allocated to each partnership based on its oil
and gas reserves at March 31, 2001. The purchase price will be allocated among
the limited partners as though the partnerships sold their assets and liquidated
in accordance with the partnership agreements.

As previously noted, if the limited partners of the partnerships approve the
mergers, Pioneer will acquire additional working interests in wells
predominantly located in the Spraberry field in the Permian Basin of West Texas,
a significant core area for Pioneer. The mergers will allow Pioneer to further
consolidate Spraberry operations and reduce production costs.

The cash distribution that otherwise would have been mailed to limited partners
in late June will be made to holders of record as of July 9, 2001 and will be
mailed on or near July 12, 2001. Final merger values will be reduced by an
amount equal to this distribution because Pioneer's offer is based on reserves
and working capital as of March 31, 2001. The distribution will be slightly
delayed to allow ownership changes to be reflected in the record of holders. To
be reflected, complete paperwork must be received no later than July 9, 2001. No
further ownership changes will be accepted until after the vote has been
tabulated.

Pioneer USA will consider offers from third parties to purchase any partnership
or its assets. Those who wish to make an offer for any partnership must
demonstrate to Pioneer USA's reasonable satisfaction their financial ability and
willingness to complete such a transaction. Before reviewing non-public
information about a partnership or its assets, a third party must enter into a
customary confidentiality agreement. Offers should be at prices and on terms
that are fair to the partners of the partnership and more favorable to the
limited partners than the price and terms that Pioneer has proposed. Persons
interested in making an offer should contact Timothy L. Dove or Mark L. Withrow,
Board of Directors, Pioneer Natural Resources USA, Inc., 5205 North O'Connor
Boulevard, Suite 1400, Irving, Texas 75039 (972-444-9001).

Pioneer and Pioneer USA anticipate mailing the offering materials late this
summer. The mergers will require the approval of a majority of the limited
partners in each partnership (two thirds of the limited partners for two of the
partnerships). If approved, Pioneer anticipates closing the mergers during the
third quarter of 2001.

A registration statement containing a preliminary proxy statement/prospectus
relating to these shares of Pioneer common stock has been filed with the SEC but
has not yet become effective. These securities may not be sold nor may offers to
buy be accepted prior to the time the registration statement becomes effective.
This press release shall not constitute an offer to sell or the solicitation of
an offer to buy nor shall there be any sale of these securities in any State in
which such offer, solicitation or sale would be unlawful prior to registration
or qualification under the securities laws of any such State.

PIONEER USA WILL SOLICIT PROXIES FROM LIMITED PARTNERS TO APPROVE THE MERGERS
ONLY WHEN THE PROXY STATEMENT/PROSPECTUS IS FINAL AND DECLARED EFFECTIVE. NO
SOLICITATION WILL BE MADE USING PRELIMINARY MATERIALS. NONETHELESS, COPIES OF
THE PRELIMINARY 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.

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INVESTORS ARE URGED TO READ THE PROXY STATEMENT/PROSPECTUS OF PIONEER FILED WITH
THE SEC, WHEN IT IS FINALIZED, 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. INVESTORS MAY ALSO OBTAIN
THE PRELIMINARY AND (WHEN FILED) FINAL PROXY STATEMENT/PROSPECTUS AND OTHER
RELEVANT DOCUMENTS RELATING TO THE PROPOSED MERGERS FREE THROUGH THE INTERNET
WEB SITE THAT THE SEC MAINTAINS AT www.sec.gov.

Pioneer is a large independent oil and gas exploration and production company
with operations in the United States, Canada, Argentina, South Africa, Gabon and
Tunisia. Pioneer's headquarters are in Dallas. For more information on Pioneer,
visit Pioneer's website at www.pioneernrc.com.

Except for historical information contained herein, the statements in this Press
Release are forward-looking statements that are made pursuant to the Safe Harbor
Provisions of the Private Securities Litigation Reform Act of 1995.
Forward-looking statements and the business prospects of Pioneer Natural
Resources Company are subject to a number of risks and uncertainties that may
cause Pioneer's actual results in future periods to differ materially from the
forward-looking statements. These risks and uncertainties include, among other
things, the necessity for limited partner approval of the mergers, which the
limited partners may withhold in their sole discretion, volatility of oil and
gas prices, product supply and demand, competition, government regulation or
action, litigation, the costs and results of drilling and operations, Pioneer's
ability to replace reserves or implement its business plans, access to and cost
of capital, uncertainties about estimates of reserves, quality of technical
data, and environmental risks. These and other risks are described in Pioneer's
10-K and 10-Q Reports and other filings with the Securities and Exchange
Commission.