I have a 85 4x4 f-150. When I put on the park brake and release it, the right rear brake seems to drag on the right side, sometimes it seems to release other times it feels like its dragging( feels hot after driving). The brake shoes look fine and parking brake releases ok. With it on blocks I turn the wheel and it will spin freely but sometimes it will lock while turning, but if I roll it again it will turn freely again. I dont feel any up and down movement of the wheel bearing, but I feel in and out movement(only on the right axle). I removed the differential cover(8.8 in.) and removed right rear axle. The differential pinion shaft seems to have some scoring on one end where the pinion gear rides but I dont see any scoring on the inside of the pinion gears. The drive pinion also seems to have a lot of slap when you turn it back and forth and yolk seems a little loose on shaft(needs tightening). My question is, do you think it is the differential that is causing the problem it obviously has wear on the pinion shaft. Can it be fixed with shimming the side gears, replacing pinion shaft and tightening the yolk nut or do I have to dig deeper and pull the whole differential out.

 

 

More than likely you have the right side emergency cable sticking or the shoes are sticking . Inspect all the brake shoe parts & cables before you delve into the rear end .