hello everyone, i just joined this forum because i have some questions i need answered. i am starting on a cummins conversion on a 1977 gmc medium duty truck. this truck originally had the the 427 big block with the allison transmission. the motor is out and i'm looking for a donor truck or drivetrain for the swap. that is where the project is at the moment. i was wondering if anyone here has done a similar swap in a big truck like this and would have info/resouces that would help me in this project.

 

IMHO, best place to start is a medium-duty with a cummins. Freightliners (FL60/70) often came with them. So did some of the later (93+?) Ford Cargo cabovers. Those setups often had 6 or 7 speed manuals.