Both the intake and exhaust camshafts are serviced in the exhaust cam position, and the camshaft to actuator position must be held to ensure the chain does not jump on the actuator. The camshaft to actuator retaining bolt is only accessible with each cam installed on the exhaust side of the head. Once either camshaft is installed on the exhaust side of the head. Once either camshaft is in the exhaust position, GM-50793 engages the slots in the face of the actuator, and bolts to the cylinder head and cover to hold the actuator in position for the actuator bolt to be removed or installed. Holding the actuator ensures the bolt can be serviced without damaging the actuator internally, and prevents accidental chain jump when holding only the camshaft hex. GM-50793 applies only to 2.0L (LTG) and 2.5L (LCV) engines.