i would say about 88-92 360's are pretty much the same as what is in the truck. you can run older 360's but they might not have a roller cam which is not a big deal but your intake should still bolt right on. you could also run a 93 and newer 360 but it may require you to get special heads which are drilled for a LA engine intake.the 93 and newer engines have better flowing head which make for more power but that is really about all that changed.