6.6L Duramax Engine Identification by VIN Number

Many model years were crossover or transitional years for the Duramax diesel, thus it is often necessary to decipher the engine model/version using the vehicle's VIN number. The chart below may be used to identify which Duramax engine your truck has based on the 8th digit of the vehicle identification number (VIN). Note that this is the vehicle identification number, not the engine serial number. The VIN number is located on the driver side door pillar, the driver side dash-mounted VIN plate, and the vehicle's title or registration card. It is important to identify which engine your have under the hood because not all components are identical nor interchangeable and may be specific to your engine version.

6.6L Duramax Diesel VIN ID Chart

Duramax VIN number sample
Sample VIN number for Chevrolet & GMC vehicles
Applicable Model Year(s) 8th Digit of VIN 6.6L Duramax Engine Variation
2001 - 2004 1 LB7
2 LLY (introduced mid-year 2004)
2005 2 LLY
2006 2 LLY (2006 variant) [1]
D LBZ (introduced late 2006)
2007 D LBZ
2008 - 2010 6 LMM
2011 - 2016 8 LML
L LGH [2]
2017 - 2021 Y L5P

[1] 2006 LLY differs greatly from 2004/2005 model; lack of part compatibility between 2004/2005 and 2006 model year LLY.
[2] LGH found in Chevrolet/GMC chassis cabs and Savana/Express van applications only; not available in pickup models.