Body Twist AND Shout

I have a huge problem with my 90 gt. This is gonna be the deciding factor if I keep it or not. The body creaks and squeaks and pops. In the right rear. Its really imbarassing. I have a stock suspension set-up on the vehicle. 3years ago my friend drove it for 5mins and was t-boned. dead on the rear axle. The lady was moving about 30-40mph. I think the poping is coming from the hatch only on right turns with a dip. As for the creaking when I slowy take off the body twists. Please tell me how I can fix these problems. Evrything from sub conn. to weatherstrips.

PSONT LET FRIENDS DRIVE YOU VEHICLES OR THEY MAY GET F#*ED UP.

CHARGEPONY

It was my friends fault he pulled out in front of her. It was at a body shop. The body had to be pulled slightly but the main hit was on the axle causing the body to shift. But that was 3years ago. This is just something that has gotten worse in the last 6months. I would like to know if sub conn. will help with the twisting as well as up and lower control arms perhaps a panhard arm. Something to stiffin her up....