2004.5 – 2007 LLY / LBZ 6.6L

The LLY (2004.5-2005) and LBZ (2006-2007) 6.6L Duramax engines brought significant improvements in power and durability. The LLY introduced enhanced cooling and the LBZ further increased power output, making these models highly sought after for their balance of performance and reliability. Key identification markers include the variable geometry turbocharger and the introduction of the EGR system in the LLY.