The noise seems to be caused by the main insulated brake cable moving in a wire bracket above the rear tire......and, or a thin metal clamp on the insulated break cable where attached to the body midway under the left side. The wire bracket above the back wheel has noticeable wear (rubbed the paint to bare metal).
I have tried almost everything, simply to rule possibilities out. Unfortunately, I didn't notice it until it was out of warranty.
I have heard GM came out with fix for it, anybody have any insight?