The museum's X-10 is the only one still in existence.
North American X-10
The turbojet-powered X-10 tested flight characteristics and guidance, navigation and control systems for the planned SM-64 Navaho. The Navaho was intended to be a ramjet-powered, nuclear-armed cruise missile launched by rocket boosters. North American built 13 X-10s, and the first X-10 flight occurred in October 1953. One X-10 flew at Mach 2.05, a remarkable achievement for the time. In 1957 the Navaho program was cancelled as Intercontinental Ballistic Missile (ICBM) technology matured.