Rattle, clatter

The most common suspects are probably the shock absorbers and bushings, and anti-sway bar links if it has a rear anti-sway bar. Broken exhaust hangers can let the pipe hit the body too. You may be able to identify that by pushing on the tail pipe. If there's nothing obvious, have the brakes checked. Automatic adjusters and springs can rust apart and rattle around inside the drum.

Thank you caradiodoc for the effort you made answering my post. Your suggestions all sound reasonable and give me a place to start. In fact I just looked under my T Bird and found both exhaust seemed pretty tight and when I shook them I couldn't reproduce the rattle sound.. As soon as I can I'll get under the car and take a closer look.

caradiodoc

After your suggestions I got down under my TBird for a up close look. Just like you said! "anti-sway bar links" .

Both anti-sway bar links are missing the (I'll call them rubber isolators). As soon as I pushed on one I immediately recognized the sound.

Is it normal for those isolators to fall out at 45,000 miles?

Add the Ford T Bird to your expertise list.

Hopefully I can just replace the isolators.

Thanks again for your help.

It's not so much the mileage as it is the age. The rubber deteriorates just like an old rubber band. The bushings will split, then crack apart. They come with the new link and aren't very expensive. You can reuse the old metal link but most of the time the nut on the end is rusted tight and the stud twists off.