Quote: For what its worth I have the same problem with my 73 Challenger. The vibration is rpm related to driveshaft speed. This is why the speed which it occurs changes with gear ratio. I have changed,balanced,swapped the following. Rear pigs & ratios,axles,drums,wheels & tires,driveshafts,trans & engine mounts. The difference is mine is a 4 speed. I can push the clutch in and it still vibrates. My u-joint angles mirror each other +1.5,-1.5. The only part I haven't swapped is the transmision. My bellhousing is dialed in both on center and square to the crank within .005". Sounds very similar. My bet (though I've never seen it) is the problem lies inthe outputshaft/tailshaft area. Doug
