05/31/2010. Remarks by Johan Visschedijk: "The Model 1049A-55-86 became the USAF main AEW version as the RC-121D-LO, of which 72 (s/n 52-3411 to 52-3425, 53-533 to 53-556, 53-3398 to 53-3403, 54-2304 to 54-2308, and 55-118 to 55-139) were procured through diversion from Navy WV-2 contracts. One more (54-183) was obtained by in-service modification of a C-121C.

The RC-121Ds differed from the RC-121Cs in being fitted with tip tanks, and in having their equipment and crew stations revised. In 1962 they were redesignated EC-121Ds, as the E (Special Electronics Installation) prefix better reflected the aircraft's mission than the R (Reconnaissance) prefix. Some later became EC-121Hs, EC-121Js, EC-121Qs and EC-121Ts."

Span: 126 ft 2 in (38.46 m)
Length: 116 ft 2 in (35.41 m)
Height: 27 ft 0 in (8.23 m)
Wing area: 1653.6 sq.ft (153.62 sq.m)
Weight empty: 80,611 lb (36,565 kg)
Loaded weight: 143,600 lb (65,136 kg)
Max speed: 321 mph (517 kmh) at 20,000 ft (6,096 m)
Climb: 845 ft (258 m)/min
Service ceiling: 20,600 ft (2,679 m)
Range: 4,600 mls (7,403 km)