As memo serves at the beginning of the war the US lettering and numbering was of the 12" of the"block style" (edges canted 45°). The national insignia on the fuselage between trailing edge of the wing and leading edge of the horizontal stabiliser, size 24 inches. The serial number on the fin, model designation centered on the rudder in the same hight as the serial with lettering 1 inch.
In Autumn 1942 introduced the numbering determined by the squadron, numbers of white , size variable.