| Designation | Modified Role | Location | Serial / Regist. |
|---|
| C-121A | |
Pima Air & Space Museum Tucson, Arizona | 48-614 |
| | |
Planes of Fame, Grand Canyon Valle, Arizona | 48-0613 / N422NA |
| VC-121A |
Staff transport | | |
| VC-121B |
Staff transport | | |
| C-121C | |
Charleston AFB Air Park Charleston AFB, South Caroli | 54-0180 |
| RC-121C |
Reconnaissance | | |
| EC-121C |
Special electronic installation | | |
| TC-121C |
Trainer | | |
| VC-121C |
Staff transport | | |
| JC-121C | | | |
| EC-121D |
Special electronic installation |
United States Air Force Museum Wright-Patterson, Ohio | 53-555 |
| RC-121D |
Reconnaissance | | |
| NC-121D | | | |
| VC-121E |
Staff transport |
United States Air Force Museum Wright-Patterson, Ohio | 53-7885 |
| YC-121F | | | |
| C-121G | | | |
| TC-121G |
Trainer | | |
| VC-121G |
Staff transport | | |
| EC-121H |
Special electronic installation | | |
| C-121J | | | |
| EC-121J |
Special electronic installation | | |
| EC-121K |
Special electronic installation |
Chanute Display Center Chanute AFB, Illinois | 141311 |
| | |
McClellan Aviation Museum McClellan AFB, California | 141309 |
| | |
Museum of Aviation Warner Robins AFB, Georgia | 141297 |
| | |
National Museum of Naval Aviation NAS Pensacola, Florida | 143221 |
| | |
Tinker AFB Air Park Tinker AFB, Oklahoma | 137890 |
| JC-121K | | | |
| NC-121K | | | |
| EC-121L |
Special electronic installation | | |
| EC-121M |
Special electronic installation | | |
| WC-121N |
Weather reconnaissance | | |
| EC-121P |
Special electronic installation | | |
| JEC-121P |
Special electronic installation | | |
| EC-121Q |
Special electronic installation | | |
| EC-121R |
Special electronic installation | | |
| EC-121S |
Special electronic installation |
Museum of Aviation Warner Robins AFB, Georgia | 141297 |
| | |
USAF History and Traditions Museum San Antonio, Texas | 54-155 |
| EC-121T |
Special electronic installation |
Peterson Air & Space Museum Peterson AFB, Colorado | 52-3425 |
| | |
Pima Air & Space Museum Tucson, Arizona | 53-0554 |
