84 Z28 L69 700R4

At any speed and going over a good dip or any time the car extends its rear end travel (up and down), I hear a zing from the rear end. It sounds just like if you pull your lawn mower starting cord while the engine is running and you hear that metallic zing. I can't tell if it is something rubbing on something or if its a wheel bearing. It only happens over bumps and at any speed and sounds as if it is coming from the left rear wheel.

Just for the fun of it, I got out while it was parked and kicked the left rear rim near the center. I could hear the sound of something loose in it...almost as if the rim was just a fraction of an inch away from the hub and it was hitting it when I kicked it. But the wheel is tight. I kicked the other three wheels and they gave a resounding thud with no loose metal sounds. Thanks guys

 

You need to jack the car up, support it on jackstands safely and look for something hanging down that's hitting the driveshaft when the suspension compresses. It's going to be something that's hitting a moving/spinning object and the driveshaft is a more likely than the brakes / wheels.

 

I've seen drive shafts groved from parking brake parts. As jmd suggests, take a peek.

JamesC