The reason for the cancellation of the A2U-1 program was in a November 19, 1954 press release from Chance Vought Aircraft.
In part it read: " Unavailability of suitable engines for an attack version of Chance Vought Aircraft's twin-jet Cutlass fighter has resulted in Navy cancellation of a order for 96 attack airplanes.
F.O. Detweiler, president of the company, emphasized that the cancellation applies only to the attack version, designated the A2U-1. Other versions of the F7U-3 Cutlass will continue in production.
The Navy announced in Washington that cancellation of orders for 200 F3H-2 Demon fighers scheduled to be built by McDonnell Aircraft, of St. Louis, Missouri, for the A2U airplanes and for engines, engine spares, radar equipment and other aircraft components for the two aircraft totaled $372,000,000 in a revision of its jet aircraft procurement program.
The announcement said one of the reasons for the cancellations was delay in development of engines for the airplanes."
CVA-29565 F7U-3M General Arrangement. View
Looking Aft With Two 2,000 LB. Bombs On Center
Section Pylon & Outer Panel Pylon Installed. 11-3-55
Press Release and photo from the VAHF archives