not those Hydro or MJD...here is another clue
1. Designed in the mid 30's
2. The Boeing 247 and Douglas DC-2 were inspiration for this design
3. The last of the breed was retired in the early 70's
4. shared engines with other well known airplanes
5. there is only 1 that is potentially airworthy today
6. License built by 1 other country
7. Twin Engine
8. Subject of numerous paintings
9. Crew size ranged from 2 to 5
10. Served with 8 different Air Forces
11. Proved to be a versatile design...both civilian and military