The SCR-189 was a mobile Signal Corps Radio tested by the U.S. Army before World War II. It was designed for armored forces, and mounted in the Six Ton Tank M1917. The original production run of these tanks included 50 "radio tanks" but the original radio components are unknown. (maybe French? or SCR-78) so what or how many tanks were fitted with the SCR-189 also appears to be unknown.