I did use new bearings and it turned out the factory shims got it where it is now. I used the thicker shim on the side with the ring, so the ring and pinion are as tight as they can be with the factory shims. A friend of mine said that as long as the backlash is between 0.008" and 0.012" it is good and I'm at 0.009" now. I took his work for it cuz he has done countless rear ends and his Nova is EXTREMELY fast!! After we did the pattern check, the clean spots on the ring were dead center. As for the pinion, we didn't touch it aside from rotating the yoke to do the pattern check.