Chrysler Corp., ever trying to spur automobile sales, is offering a novel new sales gimmick: it promises to take over the monthly loan payments of customers who buy new Chrysler cars if the customers find themselves unemployed within a year after they bought their car.

In a test program being conducted for the next 30 days in three different cities, Chrysler has promised to pay up to $300 a month in car-loan payments for any buyer of a new, domestically built Chrysler, Plymouth or Dodge car or truck if the buyer becomes involuntarily unemployed after receiving the car.

Chrysler will guarantee a year's worth of car payments--or a maximum of $3,600--and will not require any reimbursement from the car owner.

"What it boils down to is we believe there are three basic reasons that delay people's car purchases--price, cost of money and fear of unemployment," said Tom Houston, manager of Dodge public relations.

Chrysler is testing its guaranteed payment plan in Rochester, N.Y., Louisville and Tucson. Houston said those three cities were chosen because of their unemployment rates, which are around 10 percent.

If successful, the company may expand it nationwide.

Ford Motor Co. said it would take a look at Chrysler's new program--just as it takes a look at any competitive action in the marketplace. "It is an interesting approach," a Ford spokesman said. "However, it is difficult to react to a test program" that is not nationwide.