[TylerE]

No military operates the KC-10 anymore. There are a grand total of two remaining in use as aerial firefighters.

[jefftk]

> Incorrect. The KC-10 was based on the Boeing 707. No connection to the DC-10 at all other than having 10 in the name.

I think you're confused? It's nothing like the 707, and is a trijet. https://en.wikipedia.org/wiki/McDonnell_Douglas_KC-10_Extend...

EDIT re your edit: it's still a military version, even if militaries have retired it.