The Model 339-23 was essentially the export version of the F2A-3. It had the same 10-inch forward fuselage extension of the F2A-3, and armament was four 0.50-inch machine guns. The engines installed in the Model 339-23 had been formerly used in KLM DC-3 airliners and were remanufactured by Wright. They were essentially the same engines that had powered the Finnish Model 239, but they now powered an aircraft that was now over a thousand pounds heavier.
Deliveries commenced between January and March of 1942. However, because of the urgency of the situation in the Netherlands East Indies, they were shipped to the Far East missing significant items of important equipment. While on their way to the Dutch East Indies, Java surrendered, and the four ships carrying the twenty Model 339-23s (plus one earlier Model 339D which had been retained at the Brewster plant) were diverted to Australia. They were reassembled in Australia during the spring of 1942, and the missing parts were gradually delivered. The Buffalos were initially assigned to the 5th Air Force of the USAAF in Australia, and a number were repainted in USAAF insignia. However, they never got USAAF serials.
17 of the Buffalos were passed along to the Royal Australian Air Force (RAAF) in June of 1942. They were issued RAAF serials A51-1 through A51-17. Six of them were assigned to No. 1 Photographic Reconnaissance Unit and nine to No. 25 Squadron for the defense of Perth. Between August of 1942 and January of 1943, they provided air defense in Western Australia. Several examples were modified by removing the wing guns in an attempt to save weight and improve maneuverability. None of the Model 339-23s ever saw any combat (although I do have a report of A51-6 being lost due to enemy action near Darwin, NT on Oct 29, 1942). A couple were lost in accidents--A51-2 crashed near Laverton, VIC July 1942 and A51-4 crashed Sept 25, 1942 at Derby, WA, killing its pilot. The survivors were all returned to the USAAF 5th Air Force in early 1944, where they were all scrapped.