 The penultimate and last Sturgeons were rebuilt in 1949 as prototypes for the S.B.3, a proposed anti-submarine aircraft to M.6/49, powered by two Armstrong Siddeley Mamba AS Ma3 turboprops of driving two four-bladed propellers.The engine exhausts were directed downwards instead of to the rear.Another major modification was the grafting on of a gigantic bulbous nose that housed two radar operators in stations forward of the engines and the radar itself, below.