Gen II HF V6 engines use roller-chain timing chains. To service the camshafts, valves, springs, seals, or actuators in-vehicle, the timing chain position and tension must be held in the original position. Due to the closer actuators and reduced clearance to the cowl compared to current HF V6 engines, along with the change from a stacked-link chain, existing timing chain retainers will not fit the Gen II engines. GM-51333 features left and right timing chain retainers that engage the timing chain between the links and the edges of the cylinder head (LH) or front cover (RH), along with reversible crossbars to engage parting line joints or round-cast surfaces. The threaded stem of the retainer is tightened against the reversible crossbar to hold the chain position and ensure the tensioner does not extend, allowing the actuators to be removed and then reinstalled in the original position.