Originally Posted by Hydro Junkie

No guesses, time for a new clue.
Looking for a plane:
1) This plane was developed for one thing and ended up being used for something else
2) This plane was one of the first of it's type, in more ways than one
3) This plane was so successful in it's final configuration that it beat out an ally's purpose built aircraft in the procurement process
4) This plane never saw combat but the plane it replaced did
5) One of several changes to the plane improved performance in multiple ways
6) This plane had at least three structural changes to make it capable of doing it's new task
Good Luck