 Fred W. Crimson's book, U.S. Military Tracked Vehicles () referred to the Kristi KT4a's protopype as the "Water Walker" due to its amphibious capabilities.The KT4 and KT4a units are very rare and less than 5 are known to exist of a total production that was probably under 20.The KT4 was powered by a Chevrolet Corvair 6-cylinder gasoline engine.