If you've got a rustbucket that's going to require major surgery on the sheet metal, that's not as bad as butchering up a rare vehicle that's in good condition. The hole in the firewall is considerably larger on the HydraMatic-equipped trucks for extra bellhousing clearance, there's a solenoid-type starter instead of the stomper, the crankshaft flange bolt pattern on the engine might possibly be different, (not sure about that, though), and it's going to be difficult to adapt a clutch pedal and linkage due to a different-shaped frame around the bellhousing area. There were considerably more hydro-equipped GMC's than Chevvies, but us purists just realy hate to see one that's still in running condition get a hatchet job.
Jerry
