Help me diagnose this vibration/noise problem

[Killercanary]

I bent three mainshafts in my T5 and recently upgraded to a TKO. The day I put it in I didn't make it 1/4 mile from my house and the new front universal joint let go at about 45mph, just as I starting into the throttle in 3rd gear. Well the DS loop ate my aluminum DS and its now junk and the loop was severly bent. I put my dad's stock DS that too was setup for a TKO to get it home. I noticed it vibrated badly at speeds over 75mph. I put mine on and the vibrations weren't as bad, but were still there. I also installed a set of GW LCA's. Before the LCA install, my car would bottom out all the time. Well, now the vibration is worse. Here's what it does... as soon as I hit 75mph, the car vibrates baddly, when the clutch is in its worse at that high speed, when I hit bumps and the suspension collapses I hear a grinding sound.

So here's what I did tonight. I put the rear up on jack stands and fired the car up. I put it in first and let the clutch out... it would make a LOUD grinding sound every few seconds as the car "loped". I then put it in 5th and took it to 75mph, the car shook badly. Both times in looking from the rear of the car I could see the front of the rear where the DS mounts to go down and back to normal. The DS looked to be spinning fine. My dad crawled under the car and stuck his ear on the diff. cover and said it sounded like the noise cam from the rear. We then removed the DS and started the car. I put it in second and got it toabout 3000rpms before the fluid started to come out, but there was NO noise, and my dad took a small screw driver and whlie the tailshaft was spinning he touched it with the screw driver to feel it is was "wobbling"... it wasn't. So I think the tranny is fine. I then started to spin the back tires and I could see the place where the DS bolts to has a slight wobble. Would this be the pinion that is bent? Any ideas, sorry this is long but I had to list everything. BTW- the DS is NOT hitting the loop, and the exhaust is NOT hitting the DS. Thanks!