you can buy a tailshaft housing from Street & Performance to convert it to a slip yoke. All you have to do is unbolt the transfer case, and bolt the tailshaft housing on.
A cheaper route is to find the tailshaft from a salvage yard on a trans that is broken or damaged elsewhere. I traded my transfer case for the tailhousing or if you want to go to the trouble you can also likely sell the transfer case for more than the tailhousing cost and be money ahead.