The GR.3 and T.4 are the last RAF standards of RAF GR.1s and T.2s respectively. The upgrade program included new cockpit displays, helmet-mounted sights, the ability to carry the new Advanced Short Range Air-to-Air Missile (ASRAAM) and other system improvements to further extend the life of the aircraft into the 21st century. Finally, in the twilight of their career with the RAF, 60 GR.3/T.4 aircraft were fitted with the Adour Mk 106 engine, a rebuild and enhanced version of the Mk 104 offering better reliability, maintainability and slightly more thrust.