 55 of these so-called P-51-1s were outfitted with a pair of K.24 cameras in the rear fuselage for tactical low-level reconnaissance and re-designated F-6A (the "F" for photographic, although confusingly also still referred to as the P-51 or P-51-1).Two kept their P-51-1 designation and were used for testing by the USAAF.Two XP-51s (41-038 and 41-039) set aside for testing arrived at Wright Field on 24 August and 16 December 1941 respectively.