A federal judge sentenced two defendants to a year's probation and fined a third man $1,000 yesterday for their alleged roles in trying to sell a diesel engine assembly line to the Soviet Union last year.

District Judge Richard L. Williams ordered that Paul Sakwa of the District, a former CIA intelligence officer, and Chicago-area businessman Stephen G. Carter each perform 300 hours of community service in addition to serving one-year terms of supervised probation.

Williams fined a codefendant, Gerald F. McCall of Toronto, $1,000. All three pleaded guilty March 1 to a single count of violating U.S. export laws.

The government charged in an 11-count indictment in January that the assembly line, which it said was valued at $5 million, was intended for the Soviet Union's Kama River truck complex in Siberia. Prosecutors alleged that the three defendants tried to arrange the sale through a Paris-based front set up by U.S. Customs agents.

Sakwa's attorney, Mark Touhey III, asked the judge for leniency, citing the years his client served the country as a soldier and as an employe of the CIA and the State Department.

Touhey said the media had focused on Sakwa's role in the case and said that Carter was the instigator of the scheme. "Mr. Sakwa was involved in this matter at the request of Carter," Touhey said. Sakwa told Williams he was sorry for his actions. "I'd like to apologize for all this trouble. I do believe I was negligent," he said.