2 Things
 

First, sometimes when I'm driving it sounds like my rear is "grinding", or whenever I gas it somewhat hard and it shifts it'll make a rougher "grind." I don't wanna take any guesses to what it is, though I believe it's the U joint. Just wanna get verification on that.

Two, this has only happened about 2 or 3 times, but it's 2-3 times since saturday. If I floor it, i'll get her up to about 5500RPM and then it'll shoot passed 6 Grand up to 6500. I've been babying it since. I've never had a V8 anything, so idk if that's normal, which I somewhat doubt. Or if it's time for a tranny swap.

Has your computer ever been tuned? Because if your tach is reading 6500 it's either way off and you don't have a problem, or you have a big tranny problem and someone messed around with your pcm

Well I just got the car saturday. I know it's only had 1 previous owner, and I don't think it's over been tuned. But the tranny only slips like that at 5500 and it's not all the time. So idk.

Christ, why are you taking it that high in the first place so often? Btw, rev limiter on the factory tune is 5,750 Rpm's.

On your first question, you need to try and and single out where the sound is coming from. Examples: rear brakes, u-joints, ring and pinions ... etc.

well, first time I did it was cuz I never drove a V8. I have a V6 camaro which shifted on point every time without fail. Thought the LT1 would be the same. That was the first time. Second time was a while later to make sure I wasn't going crazy. And third time was by accident. lol. It's ok. I'm learning my lesson. F-Bodies=Respect

Sounds like the situation needs further isolation and investigation..

It's definetly coming just from the right rear. I really haven't had time to get the car lifted up so I can check. I'll let you all know later what I find.