There were 4-only of this configuration of Numbered AF Airborne Command Post configuration. All with SAC. Tail Nrs -570, -579,-994, and 001 ("Balls-1"). All powered by P&W J-57, water injected engines. All equipped as tankers with receiver air refueling recepticals. Normal crew (as Airborne Launch Control System aircraft)- 9. Endurance airborne: 48 hrs (refueled).One on display at Ellsworth AFB, Rapid City SD, where three of the four were based all their operational lives. 10/10/2001 @ 16:21 [ref: 3376]