I did my motive gears myself and have been trouble free for 40k miles! dont reuse the pinion bearing. i think the master install kits have them, or if not you can get one from autozone i believe. I had trouble with measuring the backlash, so i just used the sock shims and crossed my fingers. I checked the contact pattern and it looked fine so i said screw it and put it back together. i didnt have an inch/lbs torque wrench at the time, so setting the preload/ crush sleeve was tricky but it seemed to work out ok.
hopefully you will be as lucky as i was
