As others have mentioned, it's a C-117D. Regarding that particular airframe's history/status:
It was on display 1977–2002 at the then US Naval Air Station Keflavik:
With the end of the war in Europe, Keflavik Airport became a transit point for aircraft returning from the European Theater of Operations to the United States.
— Wikipedia: Naval Air Station Keflavik
The below US Navy photo from 2002 shows the process of moving it to the Icelandic Aviation Museum. It was to be restored, but evidently that has not happened.
The caption reads:
Naval Air Station Keflavik, Iceland (Sep. 16, 2002) -- Members of the stations Fire and Emergency Services (FES) finish dismantling a C-117D "Super Gooneybird". Bureau #17191. The aircraft had been on static display aboard the station since 1977, and is to be donated to the Icelandic Aviation Museum, where it will be fully restored. U.S. Navy photo by Journalist 2nd Class Stephen Sheedy. (RELEASED) Note: As of 2013, aircraft remains dismantled and exposed to the elements at the museum.
Since at least 2019 it's been at that location you have, the Hnjótur Museum:
— Google Earth (Google Maps link)