This KB-50J started life as a strategic bomber. It was later converted to an air refueling tanker. The B-50 could not fly fast enough to comfortably stay with the B-47 during refueling. To try to improve the B-50's speed, the J and K conversion packages were installed. This consisted of installing two jet engines in addition to the four piston engines. This aircraft, a J model, has the jet booster engines, one of which is clearly visible just outboard of the piston engines.