The only I've done I drilled the rivets out. Was doing other major surgery on them anyway, betting 72 B Body brackets to sit level like A body brackets do. IIRC you will only need to drill one of the rivets out as there are rivets at either end of the track. Anyway, the roller bearings are supported by a nylon/plastic cage. Don't be surprised if the cage is partially disintegrated. I had to take a rough spare set apart just to get the cages. Mine had two big roller bearings for the bottoms of the track and some small ball bearings along the sides of the tracks.