A former D.C. mailman told a Superior Court jury yesterday that he allowed his jeep to be used in the 1980 assassination of prominent Iranian exile Ali Akbar Tabatabai because he feared the alleged triggerman who asked to use it.

Tyrone A. Frazier, testifying as a prosecution witness in the trial of three men charged with conspiracy in the killing, said Daoud Salahuddin, the alleged triggerman, told him he needed the jeep to "deliver a package."

Frazier, who was placed on probation for two years by a judge for his part in the shooting and fired from his job, said he suspected Salahuddin was involved in a drug deal and only learned afterward of the killing.

"He Salahuddin is not the type of individual you say no to," Frazier said when asked why he agreed to lend his jeep. Frazier also admitted that Salahuddin gave him two $100 bills and promised another $300 a few days later, Frazier said.

Salahuddin, also known as David Belfield, was a former security guard with the Iranian Interests Section of the Algerian Embassy here and is believed to be living in Iran. Tabatabai, an outspoken critic of Iranian leader Ayatollah Ruhollah Khomeini, was lured to the front door of his Bethesda home last year and shot by a man dressed as a letter carrier.

The three men accused of conspiring with Salahuddin to kill the ex-diplomat are Ahmed Rauf, also known as Horace Butler, who allegedly helped Salahuddin obtain the jeep; Ali Abdul-Mani, also known as Lee Curtis Manning, who allegedly rented the car used for the escape; and William Caffee Jr., also known as Kalid, who allegedly wiped the car clean of fingerprints and abandoned it in the District of Columbia.

A fourth member of the conspiracy, Al Fletcher Hunter, also known as Abu Bakr Zaid Sharriff, is a government witness who has been granted immunity.

Frazier yesterday said he met Salahuddin through a friend in 1979 but only knew him casually. Salahuddin called him two days before the killing and asked if he could come to Frazier's home and talk with him, Frazier said.

Frazier said Salahuddin wanted to know how to deliver a package so that the individual receiving it would have to sign a receipt. Then, said Frazier, Salahuddin asked to borrow the jeep "for a few hours. He said nothing would happen to the jeep and led me to believe it would be returned to me."

Salahuddin also proposed that Frazier tell police that two white men had kidnaped him, Frazier said, admitting that was the story he originally told police when questioned several hours after the killing.

Frazier said Salahuddin told him that he would be driven to Baltimore and then back. Frazier then identified Butler, who sat in the courtroom, as the man who was with Salahuddin when Frazier rendezvoused as planned near the intersection of Massachusetts and Idaho avenues NW to turn over his jeep.

Defense attorneys yesterday said they believed that Frazier's assertions that he had no idea what Salahuddin was planning was in no way damaging to their cases. They said that part of their defense arguments will be that, whatever their clients may have done, they were unaware they were involved in a murder plot.