Just banging around the internet and I knew/know some guys who flew the Demon which as you may know, was like a lot of the 1950 era fighters.. very limited by its engine and the engine proposed did not come up to expectations. Also, an engine replacement required almost dismantling the airplane, not exactly user-friendly. When the J40 powered Demons came off the line, they performed SO BADLY that many were loaded on barges, shipped to maint training bases and NEVER flown. McDonnell changed to the J-71 engine, still not the best solution. Still not what McDonnell or the Navy wanted, came up with the F3H-3G or Super Demon F4H. There were different models, some single seat, some two seats. Proposals also included two J65 engines or the monster J79s. That is the picture you see and in some ways, they are correct in that in it was part of the evolution. Note that after wind tunnel testing, aero improvements included the dihedral and dogtooth wings as well as the horiz slabs with anhedral. It was, to say the least, a work in progress.

FWIW, McDonnell planned to call the airplane "Satan" which for some reason didn't impress a lot of people in DOD or Navy.

One site:
Welcome To the Warbirds Resource Group - Vietnam Conflict Aviation Resource Center

 

Grumman did build a two 'Super Tigers" with the J-79 engine but the Navy chose not to buy it so it never went into production. IT was in competition with the -104 for a number of countries including Germany, Italy, Belgium and Holland. They bought the -104. Grumman also proposed the Super Tiger to Canada and Japan. Again, no sale. The program folded.

One crashed in tests. The other reportedly is at the Navy Armaments Museum at China Lake.



The Super Tiger flew in 1956, went to M1.44 with the 'small' J79. Later with a uprated J-789, it bumped up to M2.04 and set an altitude record.

It seems everyone was building a "SUPER" something including the BIG SHARK Super Crusader.