My Challenger was originally a /6 904.

Rebuilt a 360, Had it balanced, 727, rebuilt
torque custom built with 2600 stall. I have been trying to fix this vibration for awhile.

Torque does have the balance weights on.
Driveshaft is new and balanced, new joints, all
new motor mount and trans mount. new bushing on tailshaft.

This vibration can be made while sitting still
reving the engine up to about 3500 rpms.feels like in the trans tunnel