No correct answers thus far; but I am awarding two bonus clues for all the participation. Thanks; Ernie P.
What warbird do I describe?
1. This airplane was produced in large numbers.
2. Numbers that might have been much greater; but it was replaced, or supplanted by, a new variant of itself.
3. Used in multiple roles.
4. One of which was as an escort fighter.
5. In fact, the design was based upon an earlier, successful fighter produced by the same company.
6. Less than five months elapsed between the requirement for a new aircraft being released and the aircraft’s first flight.