trans, wiring harness, computer, motor mounts and a whole pile of small parts are different, you could get a harness and computer from a 318 truck to use the manual trans, they do bolt up but since the 5.9 never got the 5 speed there is no computer made for it, another option would be the 5.9 computer from a 3/4 or one ton but they had extra 02s so you would need to add them to keep off the CEL. The 4.7 flywheel will only work if it has the notches for the crank sensor to read. Whatever you get you pretty much need the exact year matching trucks for donors as the body computers and such need to match. I guess what it all boils down to is finding two trucks with the same computer systems and a 3rd heavy doody truck for the actual computer.