Someone help. I have a 90 GT 3.73 rear it viberates bad over 60mph.U-joints are all good cant seem to get it .I aso had the drive shaft bal.Im missing the quad shocks in the rear could that be it?Also the rear end sits lower that the front what would cause this? Any help please.
If you're cruising 60mph, and you push the clutch in, if the vibrations stop, it's somewhere in the motor/trans....if the vibration continues, it's the driveline....first guess would be the tires, make sure they're all balanced right, you also can't adjust a trans for vibrations.
ok, then since you balanced your shaft, it's somewhere else not in the motor/trans, it's likely tires as mentioned, but could be suspension/rear end too
If you want to go with Jeremy's tire idea, you can rotate the tires and see if the issue follows the tire (if your steering wheel starts shaking badly now, chances are it is a balance issue).
Can someone post up a good way to test for tailshaft end play/bad u-joints? Just jack it up and start reefing on the driveshaft to see if it moves? Is a little play ok? Should there be no play at all?