Clicking noise while coasting under 30mph

My 06 Envoy Denali has been making a fast clicking noise coming from somewhere underneath it sounds when I am going under 30mph coasting...Its not extremly loud but I can hear the sound bounce off of cars and buildings when I coast by...Anyone got any ideas?

anyone?

Love to help you here, but there are a littany of possibilities, someone must check this onsite for a proper diagnosis. I would have the truck put on a lift and run it in gear at 30 with a mechanic under it to pinpoint the source.

I have the same problem with my 2005 envoy denali xl but only wile coasting in top gear if i drop it to third the noise stops i beleive the noise is coming from the tourque converter in OD. I hopes this help clairify the issue. Because i have been to 3 dealerships and im getting the typical (thats normal) answer.