Gears & Axles - help*asap*bad sound when i drive!!!

ok the other day i was driving around and a clunking noise came from the rear....and i was darn its my gears again so i parked and never looked at it.... ive been searching for rear ends and then i decide to open it and its not my rear end..... it started really quite then got louder and louder....but like i said i took off my diff. cover and everything looked fine what can it be..... thx

Sounds crazy but check the tranny mount!

ok sure will...but im starting to learn about cars.... where would it be found if its up in the air