Drive line problem...

[Tlapan93]

Hi guys. Ok so I have a weird problem. Car was converted from a Tremec 5 speed to a Lentech AOD. Install was from a local speed shop, but unfortunately the owner passed away a little more than a year ago so I have decided to try and do the wrenching myself. After about 1 month with that transmission in it, I suddenly had a metal on metal banging when I hit bumps. I diagnosed it as the drive shaft hitting the safety loop. Yesterday I found the transmission mount to be torn in half, so I replaced it with an energy polyuethrane piece, but I still have this issue. The second issue that is happening now is a horrible whinning or howling that goes higher in sound with the speed of the car. It appears to be coming from the rear end. So my question is this... Is it possible that the rear end bearing is so worn that its allowing the driveshaft to move up and down to bang on the loop and in turn would have caused the ring and pinion to shift slightly and that could have caused the gears to wear differently causing the howling? I have no idea where else to look but neither of these issues were there immediatly after the tranny swap so Im a bit confused. I have confirmed both u joints seem to be ok. Thanks for any and all input.