Two problems related to front suspension shock absorber have been reported for the 1999 Ford F-150. The most recently reported issues are listed below.
Front shocks bolt getting loose and there is a knocking noise coming from the vehicle.
Front end shocks kept coming loose. Vehicle would vibrate badly when this happened. Took vehicle back to dealer & mechanic repaired the shocks. Currently, problem with the shocks has reappeared for the third time.