I need some help. Okay so there are differences in the 1979-1980 hubs and the 1981-1985 hubs. I had one pair of each, so I wasn't worried... Until, I decided to put on the Front Range Off Road full float kit. Now I plan to use the later model hubs on the rear and the early model hubs on the front. The difference that I can see is that the size of the bolts that are used to attach the rotors to the hubs. The early models have smaller bolts and don't have the two extra bolt holes. I have heard that some folks use longer studs and a disc with a deeper set back and place the rotor between the wheel and the hub. If any of you have gone through this dilemma, I would love to hear about it. Otherwise, I will update this thread as I solve this misery - Oh I meant, mystery! Alternatively, if anyone knows where I can get a pair of the later model hubs, I would appreciate it too!