Gulf Reston Corp. said yesterday it has agreed in principal to sell all the offices, stores, rental apartments and industrial buildings it owns in Reston to a group of six giant pension funds.

The sale would dispose of all of Gulf Oil Co.'s income-producing properties in Reston. Gulf's earlier sold all of Reston's undeveloped land to Mobil Oil Corp. for $30 million.

The 22 properties involved in yesterday's deal have an assessed valuation of more than $40 million, but officials of companies involved in the sale refused to disclose the price or terms of the offer.

Gulf still owns several housing projects under construction, but has said it eventually intends to dispose of its entire interest in the community.

The tentative offer to buy the income properties was made by CB Institutional Fund III, a real estate investment group made up of six large pension funds ard managed by Coldwell-Banker, a major real estate firm.

Coldwell-Banker officials said the pension funds involved in the purchase will be identified when, and if, the deal is closed, which could be in January.

If the purchase is made, Coldwell-Banker will manage the Reston properties for their new owners, said Vincent Martin of Coldwell-Banker Management Corp. in Los Angeles.

The offer reportedly calls for the pension funds to take over Gulf's mortgages, which amount to about two-thirds of the value of the properties, and to play Gulf in cash for its remaining interest.

Persons familiar with Gulf's Reston holdings said the income properties might be sold for less than their assessed value because much of the property is under long-term leases that do not reflect today's real estate values.

Gulf Reston's income properties include 5 retail and commerical projects, 10 office and industrial buildings, 6 apartment complexes and the high-rise office building at International Center. The office building is the mst expensive, valued at $6.1 million on Fairfax County tax rolls.

Gulf's other income-producing properties in Reston the $4.2 million Lake Ann Center complex of stores and apartments, the $4.2 million Hunters Woods Shopping center and the $2.3 million Tall Oaks Center.

Gulf-owned apartments include the Crescent complex, valued at $2.9 million; the Fairway East and West projects, valued at a total of $6 million; Hunters Woods Village, $3.9 million; and the apartments in the Lake Ann complex. Also included in the proposed sale are a group of industrial buildings assessed at about $8.75 million.