rear end, tranny,axle

ok i have a 2002 ss camaro and i love the car. but latley ive been noticing certain things going wrong with it.
First of all about 6 months ago my tranny started slipping when i would get on it from a 60 roll. So i took it to a tranny shop and had the guy there rebuild it for me... Well he built it with a shift kit and that is what blew my rear end. well the guy said that wasn't the problem but I know for a fact it was. My second concern is when I did have my rear end built up my friend was driving my car at a high speed and I he was going to fast to slow down so he hit a median head on and i think he hurt something in my front end... the car drives weird now because of that.. it's hard to describe unless you drive it but when i swithch lanes he like pulls hard to other lane... do you think he bent a rim or bend something in the front end? And for the last question ever since I got my car theres always been a weird noise when I would turn my car while i was driving like making a left at a light my rear end would start knocking when its turn like i sounded like there wasnt anyfluid there. G.m. told me the rear end requires an additive. but it still sounds like that... Can someone please help me with these problems.... I love this car and never want to get rid of it. any help is appreciated:bow:

I do doubt a shift kit blew your rear out, if the rear was stout a shift kit would not really hurt things. The way it sounds, something was probably already going out and being that way, the shift kit just sped it up. As far as your pulling problem, it doesnt sound like a bent rim because the tire should "wabble" at highway speed. One tire (or both) could be slightly pointed inward, causing a one sided pull when turned. The rear end problem sounds like a spider gear or possibly a bearing inside was going bad causing the noise only on certain directional turn. Something so severe as such would easily cause the rear to fail especially with the shift kit in the trans. Im no professional by any means, but i do hope any information i've given you can help.