I am not sure how to describe the sound that is coming from my car, but the best way to describe it is metal rattling against other metal. It only happens when the car is moving and at about 1500 rpm. I was thinking maybe the catalytic converter or torque converter. Is there any way for me to find out on my own if it is one of these two things. Any help is GREATLY appreciated because the sound is annoying and embarassing.

Before we put up the car for auction on eBay or sell it on Craig's List... please pass along this info to people who actually care about low-milage, fully original, pristine condition, all-black, 1963 Ford Thunderbirds. I figured I'd start here, just in case one of you wanted it. This car only has 36,000 miles on it. That's it. It's been sitting in the same garage for 42 years and cared for well. Let me know if you're interested and the price range you'd expect to pay for this kind of thing. Thanks, Mike