Model: M561 "Gama Goat" 6x6 Tactical 1-1/4 Ton Truck. This six-wheel drive semi-amphibious off-road vehicle was originally developed for use in Vietnam. It was powered by a Detroit Diesel 3-53 supercharged three cylinder, two-stroke engine producing 101 hp. It was designed to be air-transportable and dropped by parachute.