Each of the three rocker arm assemblies contain bushings where the rocker arms are supported on the rocker arm shafts. These bushings are not serviced separately. Each intake rocker arm assembly operates two intake valves in each cylinder. Each exhaust rocker arm assembly operates two exhaust valves in each cylinder. In each set of rocker arm assemblies, the exhaust rocker assembly is the widest, straddling the intake and fuel injector rocker arm assembly. The center rocker operates the fuel injector follower.