Rattling coming from rear. What is iT?

[SlowStang2]

When I make a right turn and my car bounces a bit, a rattling comes from the rear. I was looking into doing suspension anyway, but this is quite annoying, not to mention making me nervous. So what could it be? I do not want to go spend money on a mod to fix this when it actually doesnt, so does anyone have first hand knowledge what this could be?

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94' Stang GT Convertible --Cobra upper&lower, GT-40Y Turbo Swirl aluminum heads, Mac cold air w/K&N, BBK equal length shorties, BBK offroad H-pipe, American Thunder cat-back, BBK T/B 65mm, 24lb injectors, Pro-77mm MAM, pulleys, aluminum driveshaft, 3.55s, Steeda Tri-Ax shifter, adjustable fuel regulator 14.4@100 MPH on G-tech;96 at track. (Sad, i know. This is with the stock heads)