Also, FWIW, the build date really doesn't change anything across the board. All you need to do is determine what it is... And that can be done my looking at the rear pumpkin and counting the bolts on the Diff cover (for half ton trucks). If you have 10 its a 10 bolt, 12= 12 bolt. If you have the 10 bolt for sure then all you need to change gearing is the setup kit, the knowledge, and the ring and gear. If you have a 12 bolt then it can be a little more complicated because of the 3.73 cutoff on the carrier (if you don't have a 12 bolt don't ask, lol).