In the early 1930's GMC used Pontiac and Buick engines im their smaller trucks and Knight sleeve-valve engines in the bigger rigs. A few of their off-road rigs used for mining and dam construction projects had engines that displaced 700+ cubic inches. Pontiac and Oldsmobile V8's were used in some applications in the mid-1950's.
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!