So i have this weird vibration first i thought it was the DS because it was a 2.73 car so i put in an aluminum one with new joints. still there, so upon further investigation when the vibration gets bad around 70 i put it in neutral it goes away completely but when i put it back in drive it starts again. Sometimes when the vibration starts i can put it in neutral let the rpm down slip it back in drive, and it will be gone but it comes back shortly. So i got back under it and see there's quite a bit of play in the tail shaft bushing, so my question is can a worntailshaft bushing cause this vibration when the tranny is under a load or in gear? oh ya it also seems to get worse under deceleration.

 

The tail bushing being worn can definitely cause a vibration. However I find that the main case bushing, depending on the condition of the extension housing bushing, can cause a vibration as well. Vibrations can be very difficult to track down so best of luck. Vince