The 4x4 or 4WD Auto Locking Hub Axle Actuators are located on the front wheel hubs of your Ford F150, Expedition, or Lincoln Navigator, Mark LT. These hubs connect to the axle assemblies and control how power is transferred from the axle to the fronts wheels of your truck. If your 4x4 system is not working properly a failing actuator is likely the cause. This actuator is a direct replacement for both the front right (passenger side) and front left (driver side) actuator on your Ford.