A Michigan real estate management firm said yesterday it expects to buy and then rent out 980 units of the Buckingham Apartments, a sale that could end a long condominium conversion fight at one of Arlington County's biggest residential complexes.

The complex's current owner, Chicago-based Stein & Co., has been waging a battle with tenants over its conversion plans since shortly after the firm bought Buckingham two years ago.

Richard Proffer, assistant vice president of the Hall Management Co. of Southfield, Mich., said his firm hopes to complete the purchase within a few days.

Hall is "not in the condo or co-op business. We're a rental company, which should be a relief" to tenants now living at the1,800-unit garden apartment complex off Glebe Road, Proffer said.

"It sounds terrific to me because we need to keep our rental units," said Arlington County Board Chairman Ellen M. Bozman. "Buckingham is a tremendous asset for Arlington County and it's very heartening to have somebody come in and keep it rental. Of course, the rents will have to be competitive."

Tenant leaders expressed guarded optimism yesterday about the proposed sale. "We've heard the 'no condo' statement before," said Susan Korfanty, president of the Buckingham Tenants Association. "My first concern is whether they're going to jack up the rents real high. A lot of elderly people would be particularly vulnerable if the rents go up."

Stein first offered its nearly 1,200 units as cooperatives, but sold fewer than 400. As a result, the developers wanted to convert the remaining units to condominiums. An additional 400 units owned by the Klingbeil Corp. of Ohio are rental properties.

Proffer said his firm probably will maintain the units for rental for seven to 10 years. "We might own it longer," he said, "or possibly shorter." He declined to disclose the sale price or give further details until tenants are notified.

Officials of Stein could not be reached for comment.

"If it's going to be maintained as rental housing, that's a positive thing because that's been our objective," said tenant activist John Shanley, referring to residents' efforts to assure more affordable housing for low- and moderate-income tenants. "If it's true, our efforts as a tenants' association have contributed to maintaining it as rental."

Korfanty and Shanley filed a lawsuit in February in Arlington Circuit Court, seeking to block the conversion. The tenants contended the county's Board of Zoning Appeals lacked authority to approve a request by Stein for a waiver of parking requirements that would have cleared the way for the condominium plan.

Circuit Judge Thomas R. Monroe ruled in favor of the developers, but the board later denied the waiver.