8.8 clunk

I have just put together an Explorer 8.8 for my 2000 XJ. I installed a Detriot Tru Trac and used the original 3.73 ring and pinion. I did not remove the pinion during the Tru Trac installation. I have .009" back lash and a good pattern. There is a "clunk" everytime the pinion comes around on the coast side. It is in the same place every time. I can feel a very slight tight spot just before the "clunk". There is no obvious damage on the pinion. Randy's R & P says I have a "high spot" on one pinion tooth. Where did it come from and how do I fix it?

You would need to buy another gear set.

I would take the carrier out, remove the ring gear and make sure the mounting surface on the carrier is perfectly flat. You can use a good quality file to make sure it is perfectly flat. Then make sure you properly torque the ring gear bolts in 2 steps (do half the final torque on all the bolts first then go back and do the final torque). If you still have this issue after doing this then the carrier is probably warped. It seems very unlikely the pinion has a high tooth.

My guess is the carrier(tru-trac) was mis-machined. Did you run the axle at all before the dif. install? If you can beg, borrow, or steal a dial indicator, you can pull the cover and check runout easy enough.

Edit: you could also have just gotten lucky(unlucky?) If there's a high spot on the gear, and a high spot on the carrier, you may have inadvertently lined them up. If the carrier does have excessive runout, you could try pulling the ring gear and spinning it on the carrier 180deg. The problem may go away.