Weird shimmy, Transmission

So my 95 Tacoma has aquired a noisy, semi-clunking shimmy when driving. If I press in the clutch while it is moving it goes away as it also does if sgifted in nuetral and coasting. I think this means that it is something to do with the transmission, and not an out of balance tire which is what it kind of feels like. Any thoughts?

 

Grease your zerks and see what happens.

Does it happen while braking too?

 

I'm gonna guess driveshaft center bearing and it's just a guess.

 

The U Joint sheared off the yoke on the rear diff. Apparently the guys who I have been taking my rig to for lube stuff hadn't greased that joint, so while I was driving it snapped off. Fun. Luckily it seems like an easy fix..except the yoke on the rear diff is difficult to come by without getting a whole other rear diff. meh.