Since the Hydramatic was used in numerous vehicles, it's entirely possible a pan from something like an Oldsmobile, Pontiac, Cadillac, Nash, Lincoln Continental, or even a Rolls-Royce might have been fitted to a Chevy truck!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!