Sell the transmission and transfer case as a unit and use the money to buy a nice built transmission. You can convert it but you'll have to tear it all the way down to change out the output shaft to a 2WD unit and then buy a tailshaft housing. The labor alone will cost you about $300 unless you do it yourself and then add in the parts. You can get used parts for about $100 for the two parts. Used is best because you'll probably get the sensors and pickups with the tailshaft housing. Surely somewhere in your area is a company that sources core engines and transmission for rebuild shops. In Dallas we have Bishop Industries.