The Duramax V8 engine is a family of 6.6 liter diesel V8 engines produced by DMAX, a joint venture between General Motors and Isuzu in Moraine, Ohio. The Duramax block and heads are supplied from reliable vendors of General Motors. This engine was initially installed in 2001 Chevrolet and GMC trucks, and has since become an option in pickups, vans, and medium-duty trucks. In 2006, production at Moraine was reportedly limited to approximately 200,000 engines per year. On May 9, 2007, DMAX announced the production of the 1,000,000th Duramax V8 at its Moraine facility, followed by the 2,000,000th on March 24, 2017. Engine RPO Codes LB7 RPO LB7 (engine code "1") was first introduced in 2001 and continued until early-2004. It is a 32-valve design with high-pressure common-rail direct injection and an experimental composite design cylinder head. The following trucks use the LB7: Chevrolet Kodiak/GMC Topkick Chevrolet Silverado/GMC Sierra HD Specifications Block / Head: Cast Iron / Aluminum Compression: 17.5:1 Injection: Direct; Bosch high pressure common-rail Power / Torque: at 3,100 rpm at 1,800 rpm The LLY was introduced in 2004 and replaced the LB7 completely mid-year LLY The LLY (internally called the 8GF1) (engine code "2") is a turbocharged engine which debuted in mid-2004 and continued until the end of 2005 (except the Hummer H1 in 2006). It is a 32-valve design with high-pressure common-rail direct injection and aluminum cylinder heads. The LLY was GM's first attempt to implement emissions requirements on their diesel trucks. To meet this goal, they turned to a newly developed Garrett turbocharger with a variable geometry vane system and installed an EGR Valve. Learning from problems with injectors in the previous LB7, GM changed the valve covers to allow access to the injectors without having to remove the valve covers, saving significant labor costs if injector replacement became necessary. The following trucks used the LLY engine: 2006-only Hummer H1 Alpha Chevrolet Silverado/GMC Sierra HD Specifications Block / Head: Cast gray iron / Cast aluminum Compression: 17.5:1 Injection: Bosch High Pressure Common-rail Power / Torque: at 3000 rpm / at 1600 rpm Head casting is 8gf1 Block casting is #22351021213 LLY/LBZ There are two VIN codes for the LBZ. The first is VIN 2 produced in late 2005 and early 2006. The VIN 2 engine is mechanically and physically the same as the VIN D engine but utilizes LLY engine tuning due to the LBZ