Not exactly sure on the year. He bought a 77 ford 4x4 for $1400 and the farmer threw the Chevy Grain truck in. I guess they drove it to where it was parked 2 years ago. I am planning on taking the motor out of it and putting it into my 49 (it is locked up solid). I know that it is a 47 to 53 model, that is about all I know. My dad did not know any more than that either.
Once he actually gets the bus he will let me know the dimensions. If it just plain will not work he can sell the motor and Allison automatic transmission for more than he will pay for the bus and go back to fixing up this old GMC. I will keep you guys up to date as the adventure continues.