i have the stock rearend with 4.10 gears,ta stud girdle, and cap studs. i have a vibration when i get over 70mph. it is mostly on decel. i had a spohn torque arm so i thought my pinion angle was off. so first i checked it and put it where they wanted it. didnt help. then i took out my es tranny mount. that helped a little. the vibration was originally at about 60mph and that moved it to 65mph. so i figured the drivetrain was still not lined up right so i put my stock torque arm back on. this pushed the vibration back to 70mph and faster. so each thing i did it allowed me to go a little faster but didnt fix the problem. the driveshaft was recently balanced and new u-joints were installed. but i still think it is the driveshaft in some way. i had an a4 car and when i changed the u-joints the vibration went away completely so i wonder if one of the u-joints could be messed up. could it be anything with the rearend itself. it is most noticable on decel when goin 70mph+. so i am currently at stock drivetrain angles. please help me.

 

What were all your driveline angles? Driveline angles can all be within spec but if the cancellation angle isn't correct you will get vibration.

Also when was the last time you had your tires balanced?

 

they all came in spec according to spohns directions. but now it is all back to stock so it shouldnt matter. tires are balanced.

 

I'm having the same problem; thinking about upgrading to the LS1 driveshaft in order to see if this fixes my problem....