It was, says Bud Allen, Avis Truck Rental's area zone manager, "a boner to end all boners."

On the face of it, it was just a simple mix-up Tuesday morning at Avis's northeast Washington rental yard. "One of our garagemen misread the (number) on the rental agreement" and included one wrong van in a group of seven being rented.

The vans were rented, said Allen, by a group calling itself the Iran French American Commission for the purported purpose of transporting food.

The vans were actually used, say eye witnesses, to carry signs reading "Down with Shah," as well as to broadcast the pro-shah word in downtown Washington yesterday.

One of the vans in the group, though, had been rented by the U.S. Navy in September and October, and had been returned to Avis Nov. 7.It was on the lot awaiting painting when it was rented out by mistake Monday.

And across the back of the van, carrying the political messages of support for the shah of Iran, were the words, "U.S. Navy Band."

As if that wasn't bad enough, Allen says Avis has a policy of not renting vehicles for demonstrations because they come back damaged. Four of the seven rented vans, he said, were found Tuesday parked on 17th Street NW near the White House - with all their windows smashed, "torn all to pieces."