The A-6F Intruder II was designed as the follow on to the hugely succesful and uniquely capable A-6 Intruder program. The Foxtrot would have all new avionics similar to the F-15E’s suite, including a state of the art radar (APQ-173) capable of high-resolution synthetic aperture radar and a robust air to air capability that would have allowed the A-6F to defend its self in and out of the target area via the AIM-120 AMRAAM. Further, the already heavy hitting A-6 would get a major thrust boost via the F/A-18A-D’s GE-F404 turbofans, although omitting the afterburner.
In the end the Navy would pursue the doomed A-12 Avenger stealth flying wing design for its future attack requirement and the A-6F would be sent packing. After the cancellation of the A-12, the same upgrade was offered minus the new motors as the A-6G but by this time the A-6 had gotten a bad reputation for airframe cracks and huge maintenance costs, plus its subsonic speed was seen as not ideal for the USN and the program was passed over to the also subsonic with stores but pointy nosed F/A-18E/F.
It’s always interesting to think how great of a platform the A-6F would have been on Iraq and Afghanistan with its massive fuel fraction, bomb carrying ability and side by side crew ergonomics. It truly would have been a CAS all-star! Today the A-6F protoype sits on the deck at the Intrepid Air & Space Museum in NYC.