My car is making a weird clunking noise when it downshifts into 1st gear when I'm coming to a stop (auto tranny). Not real bad but noticable. Any guesses? Hard to tell where the sound is coming from, but I'm hoping it can't be the rear end. That may not be covered under warranty since I changed out the gears.

 

Looks like from your sig that your running a stock Driveshaft still... chances are the noise is in the U-joints. I would start by checking them first.