Bid of a conundrum this. From the website of the museum: "On loan from the National Museum of the United States Air Force the museum's O-1's serial number and previous service remains a mystery. Likely constructed for the U.S. Army in the early 1950s, at some point the aircraft was transferred to the USAF. With consideration to its undetermined history, the museum's O-1 has been completed in the livery of the clandestine CIA/USAF Ravens."