F-106A 57-2480 and 57-2477 of the 84th FIS while at Castle AFB, CA escorting the second General Dynamics prototype YF-16, serial number 72-1568, technology demonstrator. Two YF-16 prototypes competed against the Northrop YF-17 for the role of the Air Force and NATO light weight fighter program. The YF-16 was selected while the YF-17 was developed into the U.S. Navy’s F/A-18 Hornet. This photo is of the YF prototype so has to after its 9 May 1974 first flight, but with still having YF on the tail makes it still a prototype. Must be a 1974 photo.