Gama Goat The Gama Goat was a six - wheel - drive semi - amphibious off - road vehicle originally developed for use by the US Military in the Vietnam War . The ' Goat used an articulated chassis , so that from distance it appears to be a four - wheel drive vehicle pulling a two - wheel trailer , but it is a single six - wheel vehicle with a four - wheel steering arrangement with the front and rear wheels turning in opposite directions . It was famous for its ability to travel over exceptionally rough and muddy terrain . The vehicle ' s nickname came from two sources ; " Gama " from the name of the inventor of its powered articulated joint , Roger Gamount , and " Goat " for its mountain goat - like off - road ability . Its military designation was M561 , 6×6 tactical 1 - 1 / 4 - ton truck . There was also an ambulance version known as the M792 that could carry four litters . History . The concept for the vehicle came when the French Army reported that the US Army trucks provided to them were woefully inadequate for the terrain in Vietnam . In 1959 , ARPA ( now known as DARPA ) funded a research project called Project Agile to develop a new tactical truck for the Southeast Asia theatre , as well as other projects of interest to the then - looming Vietnam War . Several companies bid for the contract , including Clark , General Motors and LeTourneau , but the contract was awarded to Ling - Temco - Vought ( LTV ) aerospace , best known for their A - 7 Corsair II aircraft . Final construction of the vehicles was conducted by Consolidated Diesel Electric Company ( CONDEC ) at their factory in Charlotte , North Carolina . CONDEC also had factories in Schenectady , New York , where the Gama Goat was originally manufactured , and in Greenwich , Connecticut , where the parts for the Gama Goat were produced . In the early 1960s , the company moved to Waterbury , Connecticut for a few years , then closed their plants in New York and Connecticut to move to Charlotte , North Carolina for cheaper labor and facilities . Overall , some 15 , 274 Gama Goats were built at a cost of US $ 8 , 000 each ; this was considered quite high at the time ( $ 8 , 000 in 1965 is $ 54 , 700 in 2010 ) . While the Gama Goat had exceptional off - road ability , its quirky steering made it hard to handle on pavement , and its tendency to flounder in amphibious operations required drivers to have special training in order to operate it . This meant it could not be the " general purpose " vehicle the Army had hoped for , and production was halted after the original contract expired . This is somewhat ironic , as some claim the problems were largely due to cost - cutting modifications made at the request of the U . S . Army . The air - cooled engine used in the original prototypes overheated in use , and was replaced in the production vehicles with a Detroit 3 - 53 diesel engine . The high intensity noise from the 2 - stroke diesel engine resulted in a warning to all operators that hearing protection was required while driving the vehicle . The double hull construction and complex articulated drive train made maintenance difficult ( the lube order alone took around six hours ) . In service in Vietnam , Gama Goats would often be sent out ahead of other vehicles , in order to arrive at their destination at the same time . Their loud engine noise made them much less than stealthy . The ' Goat is prized among military vehicle collectors because it is so unusual and in short supply . The vehicle was replaced by the CUCV and HMMWV . Description . The Gama Goat was 226 . 6 inch ( 5 . 76 m ) long ; had a curb weight of 7 , 300 pounds ( 3 , 300 kg ) ; had a payload capacity of 2 , 900 pounds ( 1 , 300 kg ) ; and was powered by a Detroit Diesel 3 - 53 three cylinder , two - stroke engine that produced 101 hp ( 77 kW ) at 2 , 800 rpm with a 159 . 3 in³ ( 2 , 610 cc ) displacement . It could travel at 55 mph ( 90 km / h ) on paved surfaces and traverse almost any terrain . A simple exhaust baffle was used instead of a muffler , so they could easily be heard before seen . It was designed to be air - transportable and droppable by parachute . While technically listed as amphibious , the swimming capability was limited to smooth water crossings of ponds , canals and streams due to the very low freeboard and the lack of a propeller . Propulsion in the water was supplied by the six spinning wheels , and bilge pump s were standard equipment . Drivers had to remember to close the hull ' s drain openings before swimming the vehicles . Some models had extra equipment installed which made them too heavy to swim , such as heavy - duty winches , communications shelters that made them top heavy , or radar gear . Specifications . Dimensions : Articulation : Suspension : Steering System : Variants :