The XDP X-TRA 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.Features: Includes New SealsDirect-Fit ReplacementMeets Factory Specifications2 Year/Unlimited MileageNotes: The harmonic balancer bolt will need to be removed to replace your water pump.The factory bolt is a torque-to-yield fastener (TTY) for one time use and must be replaced.