What's that light "pinging" sound???

I get it whenever the car is in motion - I can put my foot on the clutch and let the engine go to idle, put it under a heavy load (5th gear at 30) - no difference... Just a very light pinging type sound. I've pretty much ruled out detonation due to the fact that the sound is there regardless of load. I've turned off everything (including heater fan) .. Still there...

Anyone else have the same thing?

Probably won't matter after this weekend because I'll be installing the new Magnaflow exhaust - but I would still like to know whatintheheck it is/was!

Thanks Scro... I'll check it out when it's on jack-stands this weekend for his new exhaust system..

That explaination actually sounds plausible since there is no particular rhythm to the sound and the sound would be typical of an aluminum tag jingling against something..

Looked around under there and didn't find anything...