The factory front axle is a dana30, generally with an open differential.
Check the tag on the back of the transfer case to determine the model number, usually 231, 242, or 249. You can put in other models but the input shaft has to be the same, or reuse the input shaft from your current transfer case.
I build 231's all the time for jeepers to swap in to Grands to replace the 249. Sitting on a nice 242 right now as well.