For anyone who reads this i NEVER said anything about doing a burnout in reverse, this happens trying to back up slowly even slipping the clutch, so please read my original post!!!!
Sorry I think I read it in other posts. I would check to make sure you don't have broken leafs in the bundle....
One more thing
It could be the clutch, theres two things that can make problems more severe in reverse and the first is the gear ratio for reverse is lower than first and like has been stated before your rear suspension is not setup to handle much in reverse. I would try the clutch in first at idle gently letting the clutch out and see how smooth it is. Is it perfect or do you feel it try to grab in a un smooth fashion, is it quite?