HTK-C004 - US Olive Drab 41 (Early) - Standard base colour of upper surfaces of majority of USAAF aircraft from June 1941 until late 1943
HTK-C019 - Medium Green 42 - Used from mid-1942 for blotches along all edges on upper side of the wing and tail, also on the fuselage sides
HTK-C033 - Neutral Grey 43 - Standard colour of lower surfaces of USAAF aircraft in "Olive Drab" schemes from June 1941 till late 1943