Driveline vibration!!! I need help!

aka474 said

Quote: "The faster you drive the longer distance between end of tailshaft & rear end will be."

Im sorry, I just look at the diagram, I was wrong on this one. The correct is: "the faster you drive the shorter distance between end of tailshaft & rear end "

So your driveshaft either out of balance or too long. If its too long, when driving over 55MPH the driveshaft push the outputshaft forward, this caused vibration.

Click to expand...

Neither one of these scenarios is going to happen. the rear end or transmission does not change position with speed, the only thing that changes effective driveshaft length is the movement of the rear axle due to bumps and other suspension movement, and what BETTER BE DARN LITTLE that the engine/ trans may move in the mounts.