The first of two which were built. First flew in 1975. Stored at Davis-Monthan AFB in 1979. To the Pima Air Museum in 1981. 53 is a Paris Airshow code and CX001 is its Davis-Monthan park code. Returned to flying status as N15YC in 1996. Damaged in an emergency landing at Palmdale in 1998. To Edwards AFB in 2008 and preserved.