Overview: The C-9 was the version of the DC-9 used by the United States Armed Forces from 1968 to 2017. With the current versions of the DC-9 available, a C-9 wouldn’t be very accurate and it also has key differences like a larger cargo door less windows. It’s based primarily off of the DC-9-30, and if possible C-9B/C-9A difference could be a thing.
Positives: Military enthusiasts of the Aeronautica community would enjoy it. The C-9 also could have new jobs for airplanes, like medical transport (by plane).
Negatives: Not many, developers would just have to enlarge the cargo door, remove some windows, and add new jobs and reconfigure stats.
Source: https://en.wikipedia.org/wiki/McDonnell_Douglas_C-9#:~:text=The McDonnell Douglas C-9 ,U.S.%20Navy%20and%20Marine%20Corps.
The McDonnell Douglas C-9 is a retired military version of the McDonnell Douglas DC-9 airliner. It was produced as the C-9A Nightingale for the United States Air Force, and the C-9B Skytrain II for the U.S. Navy and Marine Corps. The final flight of the C-9A Nightingale was in September 2005, and the C-9C was retired in September 2011. The U.S. ...