Diesel swap out

[mecwpri]

I have an original Chevy diesel, 1982 vintage. motor and trans are long gone, bought it that way because the body is really straight and rust free. I also have a 1985 chevy van, the 25 or 3/4 ton I think although it still has the 5 lug wheels, and it has been hit in the rear. I want to put the drivetrain in the pickup. I think the trans is a 400? how do you tell the difference in a 350 and 400 trans? My next problem is the trans crossmember, seems to be mounted too far forward in the truck for this setup, do I need another crossmember or is it possible to move it back? Also the trans out of the van has a fixed yoke where the truck had a slider driveshaft I think, how do I mod this to work?Next question is what can I expect when it comes to electrical mods to make the gas motor work? Any other helpfull hints would be nice, thanks guys!