[Woodz428]

Actually the only FE's that are different are the ones in HD trucks.Their designations tell them from regular FE's,like 331,361 and 391. The 390 that would be in a pick-up(1/2,3/4) and trucks up to about a ton would be a regular FE, no different.If it is a 600 series truck then you have one. If it is designated as a 391 then it might need the bushing ,but all the others are one and the same. The main differences,that are desirable, are the forged crank, but they have to have the snout machined to accept a regular balancer. Castings aren't any heavier as far as I've seen, and the heads are really small posted.