Grinding noise 68 cuda

Check also to see if your backing plates are grooved, The shoes sit on a pad built into the backing plate, if the pad is grooved the shoes can hang up in the groove and won't allow the shoes to apply or return smoothly. 1/8" on bearings is huge play,,,,,perhaps with the load on the car the bearings are allowing to much play in the drums causing the drums to walk & rub the backing plate.