The tray with the slotted holes came from a 1978 318 4bbl police car. The shorter bolt with the taller head is for the tray with the slotted holes. These with fit a 273, 318, 360. The longer bolts with the shorter heads are for the 340 which have taller main caps. the washers make them usable on the 273-318-360. The trays interchange as long as you have the correct bolts.