Nick Hokie

I own a 1999 Z28 with an automatic, 3.23 gears, and the car is lowered about an inch. Two months ago I installed a TA rear differential cover. After changing the fluid and installing the cover, I noticed that when I put the car in reverse and turned (like backing out of a parking space) the car would occasionally make a faint screeching noise (like metal rubbing metal) from the rear of the car. The sound seems to correspond to the wheels turning (louder, softer, louder, softer, as the wheels turn in reverse). The sound does not occur at any other time, and the car seems to be driving just fine. If I put the car in reverse and backup straight, the sound does not occur either. I checked the obvious things like the cover rubbing against the rear swaybar or panhard bar. Nothing appears to be rubbing in the rear. This sound is more annoying than anything, but for my own peace of mind I would like to rule out anything being wrong with the car. Other than gremlins inhabiting the rear of my car, what do you guys think that this could be? Your opinions are appreciated. Thank you in advance.