Everything under the hood is pretty much the same when comparing the civilian and military 6.2L diesel engines. However, there are a few notable exceptions. Military Hummers don’t have air conditioning, run on a 24-volt electrical system, and have a giant generator hanging off the engine. For those equipped with a central tire-inflation system (optional on both the civilian and the military Hummers), the compressor and solenoids are located on the driver-side fenderwell. Civilians have the option of a GM 6.5L diesel, a 6.5L turbodiesel, or a 5.7L gas engine.