no,you would have knocked the plug out of the end of the yoke itself
on the trust bearing you need to check the thrust suface of the crank as well as the bearing side clearance.
the crank/flex plate/TC can move but the rest of the tranz is not going to move.
a conversion joint of 2 diff size in 1 can cause them to vib...if thats what you have in one end of the shaft.
are you sure the ring on the damper has not sliped and is off on balance now?
have you check pinion angle on the rear and drive shaft? that could be off if its raised up in the back.