LOL, ya i hope it the drivshaft and not the diff. The guy that did the install has done a lot of toys and has never had a problem with them ( i know a cupale of the guys) so i needed a reason to beef up the rear shaft so off to the steel yard for some new tube then some welding then to get it balanced. O-ya and the drivshaft now is stock but i shortened it after putting the dual Cases and never got it balanced.