Pix are real small, but that front wheel looks to be a 10 bolt pattern. Looks like a bit longer frame than my 2-ton 370, but then again it's got a lower side on the dump box than my truck too.
The manual shows that the heavier trucks used the Budd, stud centered wheels, while lighter trucks used hub centered wheels. 6 & 10 bolt patterns respectively, but it's not terribly clear.


In the 55-59 truck manual it says that there were three engines, the 270 & 302 6's, and a 347 V8. I'd bet that truck has the 270, but I'd hope for a 302 myself since my expereince finding 270 parts has been less than fun.

1956 GMC 370 dump " 'Tater "
1970 VW Volksrod "the Black Bomber"
2007 Chevy Avalanche
2020 Jeep Cherokee Trailhawk,
2005 Harley Davidson FLHTCUI

I dig all cars, old and new, whether they were hammered out of American iron, German steel, or Japanese tin cans. Being unable to appreciate them all is missing out on a world of great things.
But thats just MY opinion! :P