On certain trucks, the rear axle hub bolt(s) could break and cause the axle shaft(s) splines to wear. Over time, this could cause the splines to break. If this happens, there could be a loss of power to the wheels. Additionally, if the truck is parked and the parking brake isn't applied, the truck could roll away.
A loss of power to the wheels could increase the risk of a crash. A parked vehicle that rolls away could create the risk of an injury or a crash.
Ford will notify owners by mail. The corrective actions for this recall are under development.