Ok guys im back with the same vibration as my earlier post. I pulled the rear end from the car and took it about thinking it was bent axles. Replaced both axles,seals,bearings. also replaced pinion bearing,seal,crush collar, and nut.Got the preload i need on the pinion so its good there. My problem is the vibration is still there. It gets worse with speed. Could this be the driveshaft is out of wack? i have been running theses 4.10s for about 2 years with 0 problems. If it was the shaft shouldnt it have started earlier on? Would it be a good idea for me to get an aluminium unit? just need some help here. thanks