Engine Block Specifications. Casting Numbers: 12566910. Material: Aluminum. Displacement: 5.3L / 325 cid. Bore Dia. 3.780 in.

The LM4 was also known as the Vortec 5300. L33. The L33 was introduced in 2005 as the "High Performance" 5.3L engine. It was only available in the 1/2 ton, 4WD, extended cab Silverado and Sierra until 2007. The L33 was known as the Vortec 5300 H.O. For specific details about these engines, please follow the links below: Chevy LM4 Engine Specs

The LM4 and L33 are as light as the LS1/LS6, but have thicker cylinder walls to handle boost and nitrous. 850 hp. can be supported with upgraded internals. Although the LM4 has an aluminum block, the rest of the parts are common to the. The high-output L33 used flat top pistons, full floating rods, and 2.000 in. intake valves.

The LH6 replaced the LM4 in 2005. It was the first Gen. 4 LS truck engine and offered Active Fuel Management (AFM). The LH6 was available in GM mid-size SUVs until 2009. It was also available in GM pickups from 2007-09. It was known as the Vortec 5300. LC9. The LC9 was introduced in 2007. Originally, it was a flex fuel version of the LH6.

LR4. The LR4 was introduced in 1999. Along with the LM7 and LQ4, they were the first LS truck engines.The LR4 was available in GM pickups, vans, and SUVs until 2007.

Chevrolet's 3rd and 4th generation small block engines are generally known by their RPO code. You can determine the RPO code if you have the Vehicle Identification Number (VIN) from the original vehicle.

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The following specs apply to RPO codes: LS1; LS6; LM4; L33 **Click the blue links in the table for more detailed information**

LH6 The LH6 replaced the LM4 in 2005. It was the first Gen. 4 LS truck engine and offered Active Fuel Management (AFM). The LH6 was available in GM mid-size SUVs until 2009. It was also available in GM pickups from 2007-09. It was known as the Vort... Intro to the LS2, L76, LFA, and LZ1. LS Family = Gen. 4, 6.0L, Aluminum Block, Truck Engines

Application Information. VIN 8th Digit. Year. Make. Model. B. 2005-2007. Chevrolet. Silverado 1500, extended cab, 4WD. GMC. Sierra 1500, extended cab, 4WD