The B-17G brought together every improvement of the program in the final production version: it added the remotely-operated Bendix chin turret — inherited from the experimental YB-40 — raising defensive armament to thirteen .50-cal guns, and rearranged the cheek turrets so they would not interfere with it. Late production blocks received the "Cheyenne" tail, giving the tail gunner a wider field of fire. With 8,680 built it was by far the most numerous version and the basis for dozens of postwar conversions (transport, drone, reconnaissance, testbed, VIP transport…). 85 aircraft went to the RAF as the Fortress Mk.III, several fitted out for electronic countermeasures.