posi rebuilt?

I would do an entire upgrade to the differential actually. I had my 3.73's put in around 70k miles and within 200 miles of my break in period the stock differential did just that..break!. The shop said it was a freak coincidence, but I don't know for sure. But at the time I was given a choice of doing a rebuild of the stock differential (for about $100), or upgrade to an Auburn Pro which is a much better design (for about $400). I went with the Auburn and never had any further issues...just passed 94k miles with it.

It may sound like alot of $$ now, but if your buddy is seriously planning to mod the car, perhaps run some DR's or slicks in the future it's just a peace of mind knowing that you won't grenade your rear end as easily.

I don't intend to replace the clutches in mine at 80,000 miles, so I would say don't bother with it unless there's some evidence that they are worn out.

I just replaced the whole unit in mine i believe if you are going to get the orginal rebuilt why not buy a new locker??