For the vast majority, the stock Humvee® HMMWV® Military Vehicle that is available to the public comes with a GM 6.2 or 6.5 liter non-turbo naturally aspirated diesel engine, and a 3-speed automatic transmission. While this configuration takes care of most people's needs, those who live in higher elevation where the air is thin may experience reduced power output. Black smoke when climbing steep grades due to not enough air available to mix with the fuel correctly for optimum power may occur. The availability of only 3 gears in the stock transmission also limits your top speed and power range to a level that for some folks is less than ideal on today's higher speed interstates...especially in higher elevation areas.

The stock Humvee® HMMWV® Military Vehicle also comes with full-time 4WD, without the option to select 2WD. While this is not a major problem, as there are many newer vehicles that sport full-time 4WD which give much better traction and stability, it can lower the fuel economy and results in more wear on driveline components. Upgrading to the Duramax®/Allison® powertrain gives you a hillclimbing, clean burning, powerful responding turbocharged engine, with a higher top speed and better power delivery by shifting through a upgraded more modern 6-speed Allison auto transmission, and a 2WD/4WD selectable transfer case for the ability to do burnouts, spin donuts...err, I mean save wear and tear and increase your fuel economy...and stuff like that.

The power output, the speed limitation, the fuel economy... honestly everything about the entire driving experience dramatically changes with the Duramax® / Allison® combo. For those who want to truly wake up the beast in these loyal, tough, iconic combat machines, upgrading the powertrain brings them to a whole new level.