I'll try my best to explain.
ya know how a clutch can chatter. well sometimes when engaging my clutch the car chatters so violently that you can feel it shakin the car and I have to put the clutch in to settle things down.
this shaking occurs only under low speed engagement when I am trying to be smooth. When I let it rip it seems fine. Also, when the car moves at low speed in any direction I hear a loud knock against my tranny tunnel. It feels like the tranny mount is shot or the motor mounts but these are all not only fine but new.
Last night flying through a tunnel I revved out a couple gears and then just put the clutch in and coasted. I could hear sumthin knocking against what seems to be my tranny tunnel (like down by the passengers feet).
All serious speculations are welcome.

 

worn out or broken engine, tranny, or differential mounts.

I would also check the flywheel for glazing if it only happens when the clutch it engaging/dis-engaging.

 

I would totally agree with this assessment.

If its coming from the passenger side, the its probably that motor mount.

Almost every one of these engines I have taken out one or both of the mounts are shot.

Does the gear shifter wooble alot?

When it does this, you should have a friend idle the car for you while you inspect the travel of the motor mounts.

Its really easy. BEcause There shouldn't be any violent travel in either mount at all.