The official notice
Defect
On certain vehicles, a mounting bolt for the rear axle housing could break. If this happens, the axle housing can move and cause clunking or banging noises and vibrations from the rear of the vehicle. It could also cause the driveshaft and axle shafts to disconnect. This would result in a loss of power to the rear wheels and the vehicle could move when the transmission is in Park, if the parking brake is not used.
Safety Risk
A parked vehicle that rolls away could create the risk of an injury or a crash. A loss of power to the wheels could increase the risk of a crash.
Remedy
Ford will notify owners by mail. For Police Interceptor Utility models, you will be instructed to take your vehicle to a dealership to replace a bushing and the rear axle housing cover. For all other models, you will be instructed to take your vehicle to a dealership to update the engine control module (PCM) software to set the parking brake when the transmission is in the Park position.