On certain Ford and Lincoln SUVs and trucks, the 4-wheel drive system can become inoperable when an original equipment 4WD locking hub actuator fails to engage the inner axle shaft. The actuator malfunction is typically caused by the failure of the hub diaphragm material, which wears out over time from fatigue and ozone degredation. This Dorman OE FIX 4WD actuator kit features an upgraded diaphragm material that is more resistant to wear and environmental contaminants than the factory diaphragm. The kit also includes a new vacuum solenoid for precise engagement of the 4WD system when conditions demand. This kit helps restore proper actuator vacuum performance and 4WD locking hub operation. The kit is engineered to match the fit of the original actuator and solenoid for a complete, long-lasting repair.