In your opinion, which set of specs should I use for backlash, preload and torque? The GM manual I have, or the mfg. like Richmond, USA Gear, West Coast Differential, etc.? Its not that there is that big of a difference, but there is a difference. Is .002 to .004 a big enough difference to make a change? I would say.... yes in my line of work, but didn't know if there is a "grey area" in the Ring and Pinion set up world. I am using all new bearings, races and seals, a used set of gears (Richmond 3:73) and a used but checked and verified Auburn 28 spline carrier. The torque spec for the ring bolt torque from the aftermarket sources is 65 ft lbs, but the manual says 80-95 ft lbs. Again, which one do I follow? I used the pinion shim from the gear set that I got, (OE pinion shim from the rear differential was .038 and the one with the gears was .034, hence the first question) and set pinion depth and pinion bearing preload to 12-15 in lbs. Manual says more. (15-30 in lbs, but with a different gear ratio which spec do I go by?) I installed the carrier, and set at .000. I measured backlash and it is at .010. (Aftermarket sources say .006-.010, Manual says .005-.008) I did not have the bearing caps installed or torqued. (Again, Aftermarket says 60 ft lbs but Manual says 40-65 ft lbs) So I installed them and torqued them to 65 ft. lbs. I figured 5 ft lbs is not going to hurt anything. That changed the backlash measurement to .006. Is it suppost to change from torquing of the carrier bearing caps? I used the caps that we in the differential originally, although I do have the caps from the differential that the gears and carrier originally came out of. I am also going to install ARP Studs for the bearing caps on the final build. So I this point I figured I would hit you guys up and see what you recommend. Keep going and see what the wear pattern looks like, or start over using different values and change shims and torque settings? I appreciate all your input like always guys!!