I think the artwork is based on the B-17G 'Sally B', based at Duxford. This was one of the B-17s painted as 'Memphis Belle' for the movie, in 1990. At the time, it was made to look like a B-17F, with the chin turret removed, and, as part of the payment, a ball turret was fitted, along with the earlier top turret. The aircraft was painted in OD/NG, having been in NMF, and has retained the colour scheme and markings, with the added checker cowling, and had the chin turret re-fitted.