OE Solutions™ 4WD Axle Actuator Housing by Dorman®. 4WD Vacuum Motor Cover. Dorman’s Four-Wheel Drive (4WD) Actuator Housing is quality-engineered to restore the four-wheel drive to proper operation. It includes all the hardware necessary for a complete repair. Directly compatible and built to last, this premium actuator component is right what you need to restore your 4WD functionality to superior condition. It will help bring back your vehicle’s capability to drive the front wheels when you need them most. Made to exact specification for fit, form, and function, this reliable 4WD actuator will engage correctly your front wheels on the difficult terrain and disengage when you don’t need them.