In an attempt to remain solvent, the La Vay Corp., redeveloper of Rock Creek Gardens condomimiums in Silver Spring, is attempting to sell 278 unrenovated units in the development's newest section by tomorrow night.

Television advertising heralding the quick-sale began early this week with print ads set for today and tomorrow.

La Vay sent letters last week to the buildings' current tennants offering to sell them their post-World War II, one- and two-bedroom units in "as-is" condition for under $40,000. La Vay told tennants in meetings last week that owner-occupied financing could be arranged at 17 1/2 percent with 5 percent down; investors, he said, would need 10 percent down.

"Our intention is to achieve a complete sell-out by Sunday night," said Joseph Robert of J.E. Robert Co., sales agent for the project. Robert said the key to the plan was "a decision to cut prices" and to eliminate major refurbishment.

"I didn't have much choice," said La Vay President Gerard M. La Vay. "It was liquidate my inventories or go broke."

Across Washington Avenue, in the first 227-unit section of apartments that were converted to condos two years ago, one- and two-bedroom units were sold for about $62,000 and $69,000. Recently, some units there have been resold for more than $90,000.

Bordered by East-West Highway and the northern edge of Rock Creek Park, Rock Creek Gardens was planned as a middle-income community that would be expanded eventually with new construction. Some current unit owners now are worried that the $40,000 price being offered across the street will lower property values in the area. Some are concerned that investors will buy up blocks of units and rent them to lower-income families.

"We are in negotiations and communication with them La Vay Corp. over a lot of matters," said Cilla Reesman, president of the board of Rock Creek Gardens' owners association. Reesman declined to comment further until unit owners are notified. "The board is in the process of communicating with the owners concerning our dicussion with the developers," she said.

"Like it or not, we are making housing available to $20,000-a-year people," said La Vay, who lists among his credits upper-income projects in the District's Spring Valley section and Bethesda's Burning Tree area.

Before the complex was converted, Montgomery County's housing opportunities commission tried unsuccessfully to help tenants purchase the property, then one of the largest concentrations of moderate-income housing in the lower county.