One problem related to ball joint has been reported for the 1999 Mercury Grand Marquis. The most recently reported issues are listed below.
The contact owns a 1999 Mercury Grand Marquis. The contact stated that the ball joints were replaced but the bolt that held it in place was loose and caused the carter key to fail to hold the bolt in place. As a result, the bolt neck detached while the contact was driving approximately 20 mph and caused the vehicle to stop abruptly. As a result, the contact's head hit the steering wheel. The contact suffered a whip lash that required a medical attention. The manufacturer was made aware of the failure. The vehicle was repaired by the contact who was an independent mechanic. The failure mileage was approximately 200,000.