The XDP XTRA Cool Water Pump Housing XD683 will replace the old housing on your GM 6.6 Duramax LBZ/LMM/LML. These housings are often replaced due to erosion and leaks from cavitation or corrosion in the cooling system. Each unit is made to the same stringent standards as the factory unit and is a drop-in replacement. This is for the housing only, sold without the water pump.