There were two types of fuel tank straps on 1st Gens:
Bolt in – This style was used from 1981-1990 and was a threaded rod on the driveshaft side, and it would bolt into the frame/crossmember on the framerail side.
Hook In – This style was used on 1991-1993 trucks and has a threaded rod on the driveshaft side, and would hook into a T slot on the frame rail side.
This is for the bolt on style and is used on both gas and Cummins diesel trucks.
