A couple of weeks ago my '90 244 started making a scraping that appeared to be coming from the rear. Initially I thought it was a chunk of ice/gravel/sand (winter in Iowa). The noise persisted so I removed both rear wheels, calipers, drum and inspected everything but could not find anything that should be causing the noise. Plenty of pad, rotors in good shape, parking brake shoes intact and seated correctly, no excess play in axle bearing, differential oil level ok (foamy but level is ok). The noise has become intermittent, and when I roll down the windows I cannot isolate it to the left or right. In fact, it seems louder inside than outside the car. Normally I would suspect a bearing, but if I apply either the hydraulic brake or parking brake while it's making the noise, the noise stops, then restarts when the brake is released. What should I be checking/replacing that I haven't done yet? Thanks.
Marlin