The American Cylinder Head Remanufactured Cylinder Heads for Cummins ISX/QSX ensures you are Ready for the Road Ahead , with all valve guides, seals, and valves needed for installation included. To ensure easy installation, all threaded holes are re-threaded as well as all guides, springs and cam bearings are replaced with new components. This cost effective reman engine cylinder head undergoes a rigorous 10-phase inspection and manufacturing process to ensure quality for your heavy duty application. FleetPride is your First Click in Heavy Duty .