Put the XDP Billet Coolant Block-Off Plate XD344 in your 2001-2017 GM 6.6L Duramax to permanently eliminate coolant leaks from the rear housing on your Duramax engine. The factory cover uses a gasket and over time the plate can warp, and the gaskets can corrode causing coolant leaks. The XD344 is made from CNC-machined billet aluminum and features a built-in o-ring seal for a leak-free installation. Each coolant block-off plate comes with a black anodized finish and is ready to install re-using your factory hardware.