Well, for one, the CJ5 only came with two different rear end axles. The Model 20, and the Dana 44. And, 76'-81' Jeep was using the narrow track axles, for the slim body style that the CJ's have. But, in 82', they started making the wide track axles, that proved to be safer for the vehicle, and more reliable. Both axles are interchangeable, because of the fact that the spring seats are in the same place. So, if you ever decide that you want to slip some narrow tracks in your CJ, there should be absolutely no problem with doing so. Did I explain well enough?