Thanks guys that answers a lot of ?s for me it was suggested over on the big bolt forum that the engine is a 248 GMC but I will add the engine serial # here as I should have done in the first place engine serial # is g42224. I have a axle that is currently in a 1991 school bus its an International with disk brakes but as the I already own the bus and have the elictic brake system and the rims and matching front axle I can update the brakes and rims and rear end all at the same time. The bus was a deisel with a automatic transmission will the engine and tranny in the 53 work with enough power to get her up to speed.