US Air Force (1947-now) Air Force Flight Test Center (AFFTC)Ser. No. 52-0003 "Balls Three"The High and Mighty One Juni 1964 - Edwards AFB, CA FS16473FS28915
NASA-National Aeronautics and Space Administration (1958-now) 56-6671(Robert Rushworth) Juli 1966 1st Flight with filled external fuel tanks - Edwards AFB, CA