GMC / chevrolet / duramax

Determining which Duramax engine you have is nearly as straight-forward as knowing which model year vehicle you are repairing. The Duramax engine has evolved from the original LB7 series to include the LLY, LBZ, LMM, LML/LGH, and now the L5P series. 

Using the VIN

The simplest way to verify which series Duramax you have is interpreting the VIN# of the truck. With some exceptions, the 8th digit is the engine ID and it will either be a 1, 2, D, 6, 8, L, or Y.

• 01-04.5 LB7 is a 1
• 04.5-05 LLY is a 2
• 06 LLY is a 2 (uses same injectors as LBZ)
• 06-07 LBZ is a D
• 07-10 LMM is a 6 (new body style GMT 900 series)
• 11-16 LML is an 8
• 11-16 LGH is an L (Van application)
• 17+ L5P is a Y

Example: 1GCHK29143EXXXXXX for LB7 and 1GCHK29245EXXXXX for LLY.

It is important to note that while the engines are essentially the same in their function, the electronics, turbochargers, and injectors are different among the variants. The 10th place in the VIN number identifies the model year on these vehicles. The example above shows the 2003 model year LB7 and 2005 LLY.

If the 8th digit in your VIN doesn’t match any of the above, please give us a call with your full VIN number for confirmation.

2006 LLY and LBZ Injector Confusion

In mid 2006 the Duramax changed, and with that change brought some confusion. The early 2006 engines were still called LLY but actually require the later LBZ injectors. The 2006 LLY and LBZ engines are essentially the same, so when working on a 2006 LLY you need to purchase LBZ injectors. Simply reference the model year of your vehicle when determining which injectors to purchase for your LLY and that will help bring some clarity when navigating our website or placing an order over the phone.

The LMM began use in the new body style GMT 900 series trucks in 2007, and was later replaced in the 2011 model year with the current LML. If you are using a 2011-2016 injector for a van application with a VIN code L, you need to purchase LGH injectors.


Common-rail injection debuted on the Dodge Cummins 5.9L for model year 2003, rated at 285/305 hp. The mid-2004 models marked the introduction of the updated 5.9L engine which is rated at 325 hp. These engines use different injectors (see below.) The 6.7L Cummins engine (rated at 350 hp) was introduced in the mid-2007 model year, and again uses different injectors than the previous 5.9L engines.

First, locate your vin tag. This is normally located in the driver’s door jamb. The vin tag should include the build date of the vehicle, as well as a CPL # (Certified Parts List) which will help identify your engine.

• 2003-04.5 5.9L will be a model year 2003 or 2004 with a build date before 12/31/2003 and/or CPL # 8213, 8228 or 8412.
• 2004.5-07 5.9L will have a build date between 1/1/2004 & 1/1/2007 and/or CPL # 8346, 8347, 8350 or 8351.
• 2007+ 6.7L will have a build date after 1/1/2007

Pick-Up vs. Cab & Chassis (6.7 Only)

The 6.7 engine has a few noteworthy variants that require attention, and most importantly, different injectors. You’ll need to determine whether your vehicle is a pickup with a stock bed, or a cab & chassis model. Cab and chassis model vehicles may have any variety of options instead of a stock bed, including bare chassis, flatbeds, utility box and flatbed combinations, or something completely custom. If the vehicle lacks a pickup bed, then you likely have a cab & chassis model. If you are not sure, contact us with your full VIN for confirmation. 


Power Stroke 7.3, 1994-2003

There are several variations of the 7.3 Power Stroke injectors known as AA, AB, AD, AE, AF and AO, ranging from the year 1994-2003.

Follow the table below if you are servicing 1994-1999 versions of the 7.3 engine.

AA injector: 1994-1998 F Series, 1994-1996 F Series (California), 1997-1998 E Series
AB injector: 1999 F Series, 1997-1999 F Series (California), 1997-1998 E Series. Engines built BEFORE 12/07/1998

From 12/07/1998 to 2003, the 7.3 engine requires seven AD injectors and one AE injector to be used only in the eighth cylinder – the only diesel engine with this quirk. If you are purchasing a set of these injectors from, we provide you with seven AD injectors and one AE, with clearly marked packaging to make things as simple as possible during installation.

Power Stroke 6.0, 2003-2007

If you have a Power Stroke 6.0 diesel built before 09/22/2003, you will need to select “2003” from our drop-down menu when adding the item(s) to your shopping cart on our website. If the build date is after 09/22/2003, you will select “2004-2007” instead. For reference in the garage, the 2003 injectors will have a wire guide that is white or yellow in coloration, where as the 2004-2007 will have a black or dark grey wire guide.

Power Stroke 6.4, 2008-2010

Power Stroke diesels ranging the years 2008-2010 will require 6.4 injectors. The Motorcraft OEM remanufactured injectors we sell for the 6.4 include fuel lines for added convenience.

Power Stroke 6.7, 2011-2014, 2015-2019, 2020-Current

There can be some confusion as to whether the Power Stroke 6.7 injectors are cylinder-specific, when in fact they are not. When ordering 6.7 injectors from a Ford dealership, the fuel lines are required to be purchased with the injector and are therefore are labeled cylinder-specific. In this state, the injectors and corresponding lines must be installed in the proper cylinder.

When you order 6.7 injectors from the fuel lines are not required to be purchased. Simply place the injectors in any cylinder you wish, and then pay attention to your fuel lines, ensuring they are installed properly.

Upon purchasing Power Stroke 6.7 injectors, simply select the year range from our menu that corresponds to the year of your vehicle. If the build date of your truck falls in the range of 2/22/2010-3/17/2014 you would choose the 2011-2014 year range.  If the build date of your truck falls in the range of 3/27/2014-11/4/2019 you would choose the 2015-2019 year range.  If the build date of your truck is after 11/4/2019 you would choose the 2020-Current year range.