I am looking at buying a 99 limited 4R. The rear is making a clicking and popping noise. I would like to buy the 4R but my mechanic thinks we will have rebuild the rear end. What are my options for the rear end? buy a used one? etc? I am dumb when it comes to this. Please feel free to give advise. The 4R is selling for cheap!!!!! 194K miles on it. Thanks for any help.