He asked the same question in the Q&A forum. Truck has a Dana 60 and the floor is cut out.

OP, IMHO you'll be better off removing the cab to work on the frame more easily. But before you do, position the engine as far back as you can as a 70/30 weight distribution isn't much fun to drive. You may even find the need to cut the firewall for clearance for the distributor, etc. And move the battery to below the bed on passenger side.

With the bed off, building the drivetrain, fuel and exhaust systems should be much easier. I'm guessing the Mitsubishi frame has plain crossmembers. You may need to move them around a bit. I'd suggest bolting them in rather than welding.

If you have the cash, a nice Tremec 5 or 6-speed would be my choice. The old standard A-833 is a choice, too. You're going to be building a floor, but you only have to do that once. The transmission you deal with at every drive.

Shoot, the A-500 auto OD trans would probably be a really good fit.

R.

I'd be hoping you're running 3.54s in that Dana.