My friend just got 3.73's installed in his ride, and now when he goes 70 or 90 he gets a violent shudder/shake/vibration. Is this something to do with the way his driveline was put back together .... it doesnt really seem to come from the rear , but more from the AUTO transmission. Thanks ---

 

probably the driveshaft isnt ballenced as well as it should be.

 

...made more obvious by the now, higher rate of spin. He can always try unbolting the shaft and reorienting it 180° in the pinion yoke.

 

Thanks guys, I will let him know....