Scraping/grinding sound from rear

2002 chevy 2500 hd 260,000 miles. One owner, all original bearings and brake pads. Makes intermittent scraping/grinding sound from rear upon making one complete revolution. Very pronounced on cold start rolling. Noise lessens to barely noticeable after traveling about 1 mile. No noise when rear elevated on jack stands with drive-train engaged. Sound rebound of curb is more prominent from right side then left. Sound does not change when brakes applied. Have checked pads and still 1/8" away from wear warning sensor. Rotor and inner shield seems ok. No slop movement in wheel when off ground. Have had hub off and looked at inner bearings and felt smooth. Could not remove outer bearings due to a retainer clip keeping them in place. Not sure what I should start replacing first. Any ideas/suggestions would be appreciated.