Rear diff problem?

[fastezz]

OK heres the deal, my friend just got his tranny back in and his redone transfer case at mitsu and he did a hard 6k rpms launch slipping the clutch, he is running a act 2600 btw. He will drive and if he steps on the throttle it just slips, I am almost posotive it is his rear diff, he drives a 91gsx so I am thinking it is the weak 3 bolt diff, so if anyone can help us out with this at first we thought it was a slipping clutch but it just doesnt add up it has alot of life left on his act 2600 clutch and he has a almost brand new fidanza flywheel. Let me know what you think.
Ryan

 

[BOBS90TURBO]

If the rear end was going bad, I think you would know it, it would not just be slipping like you say, and the fact it is 3 bolt means nothing, if you snapped an axle you would know, I bet he glazed the clutch disk, was it new, did he break it in, a new act can go bad.