Aording to my Chilton repair manuals, a "D" suffix letter indicates the engine is a 1958-64 283 cubic inch. I don't have a letter designation in the truck manual that covers the 68 C-50, buit the 283 is not listed as an engine option for that year model.
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!