I did a '73 1/2ton 4X4 and it was pretty easy. Its a mechanical clutch linkage and all the mounts for the pedals and everything was there. HOWEVER my truck was a small block(360) and had a divorced t-case so I just took out the short tailshaft 727 and the NP435 bolted right in. Finding a flywheel was the hardest part.
SB dodges(318,340,360) use a different bellhousing than the BBs(383,400,440).
Now you have a BB(383) and 4spd trannys for BB are next to impossible to find and VERY expensive when you do, especially a 4WD. You would pretty much need to find a donor truck. Even 4WD BB 727s are hard to find. If you can find a donor truck great go for it, otherwise I would just have the 727 rebuilt. Also finding a flywheel for a 383 would be tough, and I'm not sure if one for a 400 or 440 will work.
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'89 XJ 4" lift, Warn Combo mount and 9.5ti!
31s, 4.10s and rear lockright!
That's enough(for now!)