I have a 98 cherokee 4 door 2wd straight 6 with 128k miles. I also have a 98 grand cherokee with a locked up motor. Anyone know if I can take the front axle and transfer case from the grand Cherokee and install it on the 2wd cherokee?

The axle will swap directly over, the tcase would fit if you had a 4wd Cherokee transmission, but the grand Cherokee front axle is a low pinion which isn't worth even swapping in, and it probably has cv axle shafts which aren't strong either. I don't remember exactly which transfer cases the grands came with, but I don't think they ever had a 231. I could be wrong though.