Treasury Secretary G. William Miller said yesterday it is possible that the Chrysler loan board could give conditional approval to new guaranteed loans for the auto company before the Carter administration leaves office, but that would require a rapid agreement on major financial concessions by Chrysler's employes, suppliers and creditors.

In private meetings with officials of ychrysler, the United Auto Workers and Chrysler's bank creditors, Miller also said the company must intensify its efforts to merge with other auto companies to assure its long-term future.

A conditional approval would not permit Chrysler to draw down any of the $400 million in guaranteed loans it is seeking to remain solvent, but it would increase the chances of a favorable ruling after the Reagan administration takes office on Jan. 20.

Miller is the only one of the three voting members of the loan board who will leave the board Jan. 20. The others, Federal Reserve Board Chairman Paul A. Volcker and Comptroller General Elmer Staats, will remain and be joined by Donald T. Regan, assuming he is confirmed as Treasury secretary.

In the absence of a conditional approval by the current board, the Reagan administration might feel obliged to make a complete review of Chrysler's prospects, delaying the delivery of the new guaranteed loans, Chrysler officials say.

At his Senate confirmation hearing yesterday, Regan sounded a little more encouraging on the Chryslers issue, although he still would not say whether the Reagan administration supports more aid for the company. He called the auto industry "one of the underpinnings of the economy" and said its troubles "must be dealth with on a priority basis."

The Reagan administration opposes a general policy of bailing out failing companies, Regan indicated, but he said Chrysler "is a special situation," since Congress already has agreed to help it.

Miller agreed that Chrysler is in a desperate financial position but said his staff's analysis indicates it can survive for a month or six weeks more in the absence of the guaranteed loan funds, disagreeing with estimates by Chrysler that the end could come this month unless the loan guarantee is approved.

"It's a matter of judgment," he said, adding "I think their cash will be tight in the next 30 to 45 days." Approval of the loan guarantee is a "day-to-day question."

UAW President Douglas Fraser said he doesn't believe Chrysler's problems are "insurmountable." But the company faces a cash crisis, he said. "I don't think it's in the far-distant future." f

Fraser, whose union has been asked by Chrysler to accept a 21-month wage freeze to save Chrysler some $600 million in payroll and benefit expenses, said he agrees the company needs help from the UAW. "Certainly it's necessary. We've crossed the Rubicon on that one." But just how far the UAW will go, and what it will demand from Chrysler in return, will be left to negotiations between the company and the union which begin today, he said.

If we share in the sacrifices repeatedly, then there has to be a sharing in the good times. There has to be a sharing in the prosperity and the profits" if Chrysler recovers, he said.

Fraser and the UAW had been unwilling to negotiate with Chrysler until they heard frist-hand from Miller and the loan board that wage concessions were essential, and Miller didn't disappoint them. Reviewing the Treasury staff's latest assessment of Chrysler's economic condition, Miller told the union that the company faces a financial gap "that must be closed by concessions," one participant said.

Fraser proposed that the board approve the entire $700 million in unused loan authority approved by Congress. Chrysler already has received $800 million. But Miller noted that for each dollar of guaranteed loans it receives, Chrysler must raise a dollar of matching financial assistance from private sources. The maximum amount of matching funds it can raise this month is about $360 million, Miller told the union.