I put my 6 speed in 2 years ago. I had a custom drive shaft made for it and the car vibrated. the shaft builder said it was the trans. I paid for another driveshaft and it vibrated but less and at a different speed. I finally bought a spohn shaft. It only vibrates under coast conditions from 55mph and up. Art houser biult my 12 bolt and set the pinion angle and said the driveshaft is too short. Sometime before I need a new out put shaft bearing I would like to get this resolved. Any ideas would be appreciated.

 

The problem is Art Houser and his rear axle set up..

 

the smoothest this car has ever been is since Art did the rear