Five pre-production "Mk 2" test aircraft (serial numbers "18103"-"18107") were produced, all fitted with Orenda 2 engines; one was fitted with dual controls and designated a "Mk 2T" trainer. According to pilot Jacqueline Cochran, the Orenda engine responded noticeably smoother than any of the British or American-built jet engines that she had previously flown. Initial teething issues with the pre-production aircraft were soon resolved. The first production version, designated "Mk 3", made its first flight during October 1952. The Mk 3 incorporated the APG-33 radar and was armed with eight .50 caliber Browning M3 machine guns. The "Mk 3CT" and "Mk 3DT" were again dual control versions supplied to operational training units.