This is the first appearance of The U-Foes, a sort of anti-Fantastic Four who are transformed while intentionally exposing themselves to the same cosmic rays that transformed the FF. This kind of begs the question: If the FF have been public about how they got their powers, why aren’t more people doing this?
Anyhow, the foursome are a beefy pilot, a female “life support specialist” (because a chick can’t be a straight-up scientist, I guess), a skinny millionaire with grey hair, and a “fuel-propulsion engineer.” Sadly, their experience isn’t as positive as the FF’s. They are changed into Vapor (gaseous girl),
Vector (telekinetic), X-Ray (powered by radioactivity instead of fire, but otherwise the same as Johnny), and Ironclad (made of steel instead of bricks).
Their powers actually kill them at the end of the issue.
Creators: Bill Mantlo and Sal Buscema, with Al Milgrom listed as designer of the U-Foes
For the complete history of the MU, year by year, go here.