The Stovebolt Site Forums The Parking Lot Big Bolts 1957 ? GMC 4 X 4 2 Ton Fire truck

Not sure if a 2 ton is big enough, but gmc also offered the oldsmobile engines in the larger trucks. 371 Olds perhaps?

Are you sure the engine is a SBC? Does the engine have small hoses coming out of the water pump and going to the heads? If so you likely still have the reversed cooled Pontiac engine.