Chevrolet engine specifications follow GM conventions and the RPO code system identifies specific variants. The LS family alone has dozens of production variants with substantial internal differences. For shops working through Chevrolet sourcing in 2026, the variant identification is what separates clean transactions from costly returns.
How GM Names Its Chevrolet Engines
GM uses RPO (Regular Production Option) codes to identify engine variants. The RPO code typically appears in the vehicle's service parts identification label.
For LS-family applications: LS1 (5.7L Gen III car), LS6 (5.7L Gen III high-output car), LS2 (6.0L Gen IV early), LS3 (6.2L Gen IV current), LS7 (7.0L Gen IV Z06), LSA (6.2L supercharged Gen IV), LS9 (6.2L supercharged ZR1).
For truck LS variants: LM7 (5.3L Gen III non-AFM), LMG (5.3L Gen IV with AFM), LH6 (5.3L Gen IV SUV with AFM), LY5 (5.3L Gen IV with AFM), L83 (5.3L Gen V with AFM), L84 (5.3L Gen V with AFM and DI), LQ4 (6.0L Gen III), LQ9 (6.0L Gen III high-output), LY6 (6.0L Gen IV with AFM), L96 (6.0L Gen IV heavy-duty non-AFM).
For LT-family applications: LT1 (6.2L naturally aspirated current), LT4 (6.2L supercharged), LT5 (6.2L supercharged ZR1 Corvette), L86 (6.2L current truck with DFM), L87 (6.2L current truck variant).
For Duramax: LB7, LLY, LBZ, LMM, LGH, LML, L5P, L5D.
Reading Your VIN
The eighth character of the Chevrolet VIN identifies the engine code.
The Major Chevrolet Engine Families
The LS family spans Camaro, Corvette, Silverado, Tahoe, SS, and many other applications. Multiple production variants with substantial AFM-status and Gen III / Gen IV / Gen V differences.
The LT family in current production Camaro, Corvette, Silverado, Tahoe applications.
The Vortec V6 4.3L family in entry-level Silverado, Colorado, and older applications.
The Duramax 6.6L family in Silverado HD diesel applications.
The Ecotec four-cylinder family in Malibu, Equinox, Cruze, and other applications.
The classic small-block family (350, 305, 327, 400, others) in restoration and rod applications.
The big-block family (396, 427, 454, 502) in older Suburban, Express, and muscle car restoration applications.
What Compatibility Actually Means
Same four compatibility checks as any other manufacturer.
For Chevrolet specifically, the trap is the LS-family variant distinctions. An LS1 (5.7L car) is not the same as an LM7 (5.3L truck) despite both being LS-family. An LS3 is not directly interchangeable with an LS7 despite both being Gen IV performance variants.
The Three Most Common Compatibility Mistakes
First: confusing car LS variants with truck Vortec variants. Different deck heights, different accessory configurations, different oil pans.
Second: confusing Gen III with Gen IV LS. Cam sensor location, exhaust manifold pattern, and some accessory mounting differ.
Third: confusing direct-injection LT variants with port-injection LS variants. Fueling system is completely different.
The Practical Sourcing Workflow
Decode the VIN. Physically inspect and verify casting numbers. Source by RPO code. Confirm transmission pairing. Confirm fitment with the supplier.
The Chevrolet engines on our catalog publish RPO codes, casting numbers, platform fitment, and transmission compatibility upfront.
