So this morning I put the car in reverse (auto trans) and get this metallic grinding noise from the rear for acouple seconds. Wasn't the brakes - different type noise. I usually get the clunk into reverse which I know is common, but never this. Didn't happen later or since - we'll see tomorrow morning. Anyone else get this?

 

Hmmm...I guess it could be the transmission, I suppose, but I've also had a limited slip differential do the same thing on another car. It typically happened under slow speeds while making tight turns. Take it to a parking lot and do some tight figure eights at low speeds. If it's your differential, then you'll surely hear it.

 

I'm thinking 2 piece driveshaftor the differential?? I got this a little bit after I installed the SC. I replaced the stock driveshaft for a carbon fiber one and the metallic noise that you describe went away.