The financially troubled Chrysler Corp. presented the Treasury Department last night with a scaled-down bid for $750 million in federal loan guarantees.

There was no immediate reaction from the Carter administration, which last month rejected an appeal for $1.2 billion in loan guarantees as excessive.

The company's new bid came as the United Auto Workers offered in negotiations with Chrysler to defer the company's $200 million in pension funding payments for 1980, freeing the money to meet immediate cashflow needs.

The union also made undisclosed concessions on economic gains won earlier from General Motors Corp. and Ford Motor Co. A union aide described them as "significant" but gave no details.

In its 75-page "modification" of the earler proposal for government help, Chrysler said it "cannot be as confident now of its maximum requirement" as it was a month ago but pledged to "take extraordinary measures" to contain its funding needs to its earlier estimate of $2.1 billion over the next two years.

It revised its estimate of resources available from non-government sources to $1.35 billion from sale of assets, state and local government assistance and constituent groups such as the UAW, leaving $750 million for the government to guarantee in private bank loans.

In its reports last night, Chrysler noted a dramatic change in the economic outlook because of recent Federal Reserve Board policies to halt credit expansion. The abruptness of the changes has increased the uncertainties facing Chrysler and the urgency for resolution of the situation," the report said.

The report also said the company's projected increases in market share could be jeopardized by reduced consumer confidence in Chrysler.

The automaker said it is negotiating to sell some subsidiaries and attract new financial support from banks and local governments to cut the loan guarantee request from $1.2 billion to $750 million. Chrysler declined to disclose further details because it "could impair these negotiations."

Chrysler also revealed it has slashed advertising budgets by 35 percent.

Earlier in the day, legislators from Michigan formally introduced slightly differing bills to provide assistance to Chrysler, America's 10th largest industrial firm.

One bill -- sponsored by Sen. Donald Riegle (D-Mich.) -- would require Chrysler to establish an employe stock ownership plan in order to qualify for government guarantees of bank loans to the automobile manufacturer.

A separate measure sponsored by Rep. James Blanchard (D-Mich.) would permit a three-member government loans as well as guarantees. But the House bill contains no provision for employe ownership, a concept that has been gaining ground on Capitol Hill in recent weeks.

The Senate and House bills offered yesterday didn't specify any amount of federal loan guarantees, but both would require Chrysler to develop a long-range management and fiscal plan to give the enterprise a sound managerial and fiscal base.

Meanwhile, the UAW and Chrysler continued talks in Detroit on a new contract yesterday. Union President Douglas Fraser told reporters before an afternoon session that he was planning to make some economic concessions.

Fraser wouldn't discuss details but said the plan will "deviate from the Ford (Motor Co.) and General Motors (Corp.) agreements" signed recently. He said presentation of the union contract proposal would enable Iacocca to assure federal officials that the union indeed wants to help the company.

The Treasury announced separately that Ernst & Whinney, one of the nation's largest accounting firms, has been hired to analyze Chrysler's financial data and its financial projections.

The department also hired John Secrest, a recently retired financial vice president of American Motors Corp., as a paid consultant to help evaluate Chrysler's revamped aid request.