Delivered July 31, 1943. Seattle, Aug, 1943; Assign to Materiel Command for armament testing . Eglin Air Proving Ground, Oct,1943. The chin turret modification had been developed in the XB-40 in late 1942 (41-24341) ; and refined by UAL CHY in June, 1943 (42-5964). Entered production July,1943 (42-3483) and August (42-6155). This aircraft prototyped the production staggered waist introduced in production on 42-37989 (Nov, 1943). Assigned 8th AF,; RTN US, Bradley, 8/45; RFC Altus, 9/45.