I believe the distributor drive gear is in a different location for the 151 engines. Or at least the later model ones.
You are absolutely correct, sir! But they all have the front distributor gear as well. They DON'T have the fuel pump lobe. The later ones used an electric fuel pump to feed the electronic fuel injector.
Perfect Circle 229-1708 camshaft fits the last of the 153s and the first of the "Iron Duke" 151s!! It's a flat tappet hydraulic unit, but it proves that the two blocks were siblings at first. Unless GM moved the lifter bores or changed the angle of the bores, the possibility of interchangeability is greatly increased.
