A guy down the street is selling an 80 Cherokee. It has a 401, rebuilt 727, and dana 44 front axle. The interior is ok, the body is good, and the price is decent. The only problem is that it has an AMC 20 rear axle. Will a dana 44 from another full-size bolt in? If so, what year/model? If not what mods would need to be made?
Is there somthing wrong with the rear axle? Is the 20 broken some how. If it is then I can see why you would want to swap it out. If it is not broken then I would leave it in there. The 20s that came in the FSJ's were AMC 20HD's They were bigger and stronger than the ones taht came in the CJ's. And a HD 20 is just about as strong as a D44, in fact some may argue that they are stronger. The ring gear is larger, and the pinion is also larger. Take the money you would spend on the axle swap and get a set of aftermarket HD20 shafts, and you will have an axle that is stronger than the D44 for less money.