It really doesn't matter if you need to rebuild it. It will cost about the same minus the parts. The tailshaft will have to be purchased from the dealer, which is about $250 for the shaft. You will also need the housing. A tranny repair shop may have these used, but they may not want to remove them from a core that they have. Best thing to do is to talk to a tranny shop for their opinion on a used or conversion. Allison is a much better way to go, but you can't get one to fit on the 6.0l, if that's what you have. I think that the brand new ones have an Allison option with the 6.0, but you will still need to mate it with the 6.0l electronics, which may prove difficult to do. Remember, you still need the front axle assy and drivelines and harnesses. It can definently be done, but is this worth it to you?