By March, 1953, area rule and leading edge chamber had been incorporated to create the MX-1964 configuration illustrated by this transonic wind tunnel model. The configuration was to have a 60° delta wing with the trailing edge swept forward 10°. It was to have four engines with the two inboard units mounted on pylons under the wing and the outboard engines mounted on the wing upper surface. The fuselage was to have a 'coke bottle' shape and a small amount of leading edge camber to reduce drag due to lift. By September, 1953, the B-58 had evolved into a virtually new design with a separate pod, Siamese nacelles, wing-mounted drop tanks, and the relocation of the search radar from the pod nose to the fuselage nose. These changes helped realize a considerable weight saving with virtually no drag penalty. By August, 1954, the final B-58 configuration, four individually pylon-mounted engines and all fuel contained internally and in the podded lower component, had evolved and the design was frozen. Few major changes would transpire between the completion of the August, 1954, B-58 full-scale mock-up study and the roll-out of the actual prototype aircraft.