with the new LS7. The LS6 shares its basic block architecture with the GM LS1 engine, but other changes were made to the design such as windows cast into the block between cylinders, improved main web strength and bay to bay breathing, an intake manifold and MAF-sensor with higher flow capacity, a camshaft with higher lift and more duration, a higher compression ratio of 10.5:1, sodium-filled exhaust valves, and a revised oiling system better suited to high lateral acceleration. LS6 intake manifolds were also used on all 2001+ LS1/6 engines. The casting number, located on the top rear edge of the block, is 12561168. Applications: 3.78 in. bore blocks (1999–2007) The 4.8 L and the 5.3 L are smaller truck versions of the LS1 and were designed to replace the 305 and the 350 in trucks. The 4.8L and the 5.3L engines share the same Gen III LS-series engine block and heads (upper end) and therefore, some parts interchange freely between these engines and other variants in the LS family. 4.8L LR4 The Vortec 4800 LR4 (VIN code "V") is a Generation III small block V8 truck engine. Displacement is with a bore and stroke of . It is the smallest of the Generation III Vortec truck engines and was the replacement for the 5.0 L 5000 L30. The LR4 engines in 1999 produced while the 2000 and above models made and all have a torque rating between , depending on the model year and application. The 2005–2006 models made and , LR4s are manufactured at St. Catharines, Ontario and Romulus, Michigan. It uses flat top pistons. Applications: 5.3 L The Vortec 5300, or LM7/L59/LM4, is a V8 truck engine. It is a longer-stroked by version of the Vortec 4800 and replaced the L31. L59 denoted a flexible fuel version of the standard fuel LM7 engine. Displacement is from a bore and stroke of . Vortec 5300s are built in St. Catharines, Ontario and Romulus, Michigan. Another engine variant, the L33, shares the same displacement, but has an aluminum block with cast in cylinder liners, much like the LS1. LM7 The Vortec 5300 LM7 (VIN code 8th digit "T") was introduced in 1999. The "garden variety" Generation III V8 has a cast-iron block and aluminum heads. The 1999 LM7 engine produced and of torque. The 2000–2003 engines made and . The 2004–2007 engines made and of torque. The stock cam