The flex-plate does but do all the parts in the TC? I have not tested 4wheel yet. But I smell what your stepping in.

 

Part of it moves, part of it doesn't. When you're stopped the impeller still turns but the rest is stationary.
I see you mentioned a clunk when you put it in D or R, which makes me think drivetrain. The u-joints in particular can make some awful noises.

 

Its pretty smooth now. No clucks since the flex plate has been tightened down.

 

Finally, some closure.

 

Not really still have the "rocks" sound. Shifts smooth and motor is on point though.