In 1948 the US Army purchased a small number of these test vehicles with the designation the 'Jungle Burden Carrier' for evaluation in jungle warfare and with airborne forces.

The driver's seat could be removed and the steering column moved forward and the vehicle driven in reverse to accommodate more cargo.

The HMMWV was, however, unable to fulfill the role of the Mule, so the M-Gator, a military variant of the popular John Deere Gator vehicle, was introduced.

The variants of the M274 with respective powerplants were: All Mules had three-speed manual, non-synchromesh transmissions with two-speed transfer cases, and were four-wheel drive vehicles.

The lower speeds and high power (14 hp or 10 kW)[2] of the Mule made it a versatile off-road vehicle.