What else would cause a part throttle vibration besides u-joints? I have a m-21, new driveshaft and yoke, and the original 8.2 posi.

thanks
Mike

Broken driver side engine isolator mount or trans mount broken.
Improper driveshaft angles/phasing.

I don't know about the angles but the trans. and motor mounts are all new. Any other possiblities?

thanks
Mike