| Designation | Modified Role | Location | Serial / Regist. |
|---|---|---|---|
| YU-21 | United States Army Aviation Museum | 63-12900 | |
| RU-21A | Reconnaissance | ||
| U-21A | |||
| EU-21A | Special electronic installation | ||
| JU-21A | |||
| RU-21B | Reconnaissance | ||
| RU-21C | Reconnaissance | ||
| RU-21D | Reconnaissance | ||
| JU-21D | United States Army Aviation Museum | 70-15888 | |
| RU-21E | Reconnaissance | ||
| U-21F | |||
| U-21G | |||
| RU-21H | Reconnaissance | ||
| U-21J | |||
| RU-21J | Reconnaissance |