Re: Converting an auto trans truck to stick?
 

An M-20 would be a good trans for you because it's not a close ratio and they are pretty cheap. I recently sold one with the flywheel, pressure plate, clutch, shifter and trans for $600. They run a lot less than the M-21 or 22's. It's also nice because they have a lower 1st gear ratio which helps get those heavy rigs moving.

To answer your other question....a 400 is a turbo hydro 400 which is GM's toughest auto in those years.