LML/LGH Swap Info

The LML engine was only offered in pickup truck configurations in both the 2500 and 3500 models. This 397hp/765lb-ft configuration is only available with the Allison 1000 transmission.

The LGH is a detuned version of the LML engine and was offered in two configurations:

  1. LGH/Allison (cab and chassis trucks and fleet vehicles) These very closely resemble the LML Truck configuration and we do support these drivetrains in conversions.
  2. LGH/6l90 (vans, cutaways, busses) WE DO NOT SUPPORT THIS CONFIGURATION!!!

The LGH / 6L90 configurations were significantly de-rated (260hp/525lb-ft) in order to prevent transmission damage due to the lack of input torque capacity of the 6l90 trans. These powertrain combos are often cheaper and although there are no major internal engine differences from the LML, there are many differences in the intake, wiring, and emissions systems. Many of these LGH specific components are designed with the significantly lower power output in mind, which create significant restrictions when attempting to make power at or above the factory LML output.

For the reasons listed above as well as many others, we do not support the standalone operation of the LGH/6l90 combo. We can provide you with harnesses and modules to run “engine only” as an LML but you will have to change the upper engine harness as well as a few other intake components and potentially relocate some sensors and the glow plug co trip module. Controlling your transmission in this configuration will have to be done by some other standalone system and we do not provide wiring or Tuning support for these systems. However we know it can be done.

We strongly suggest you find a way to make the Allison work in your swap if you intend to utilize the power of the LML Duramax. If you are set on using a smaller transmission, then an earlier 2002-2010 Duramax powertrain with either a 4l80 or 6l90 is a better choice.

We could spends a lot of time explaining why the Allison is the right choice behind the Duramax, but we prefer you just trust the experts since we have an extensive amount of experience with these engines and transmissions and we can guarantee that whatever you are thinking…we have already tried it! Our goal is to ensure that your money is well spent and that you swap provides reliable performance for years to come.

Whether it’s a diesel powered race vehicle or simply a show and tow rig, let our experience help you make the right choices to save you money in the long run and ensure that you exceed your project goals!