DBohl,
There are only a couple of parts in the 2 wheel 4500 that are different than the 4X4 four wheel but I can't remember them right now. Get a hold of Quad 4X4. They can tell you anything about your transmission. As New Venture no longer makes the 4500 or the 5600, they are getting expensive. Just to buy a new OEM input shaft for the 4500 is over 500 smackaroos. It THINK your transmission can be converted easily. Quad 4X4 has all the rebuild stuff and even upgrades like I just did for mine. I updated to his Silver kit with a full spline for the 5th gear. Real nice stuff . A little expensive but worth it. My transmission will easily outlive my truck now.
WD