a cancelled order of 524 aircraft using F-series V-1710 engines, the only one built was retained by the USAAF for testing* the rest of the order was completed as P-38F-13-LO, P-38F-15-LO, P-38G-13-LO, and P-38G-15-LO aircraft. P-322-I: 22 Lightning Is of the 143 built were retained by the USAAF for training and testing. Most were unarmed, although some retained the Lighting I armament of two .50 cal and two .30 cal guns. P-322-II: 121 Lightning Is were re-engined with the V-1710-27/-29 and used for training. Most were unarmed. P-38B: Proposed variant of the P-38A, not built P-38C: Proposed variant of the P-38A, not built P-38D: Production variant with modified tailplane incidence, self-sealing fuel tanks, 36 built P-38E: Production variant with revised hydraulic system, 20 mm cannon rather than the 37 mm of earlier variants, 210 built P-38E Floatplane: A proposed floatplane variant of the P-38E with upswept tail booms and fitted with droppable and fuel-filled floats, one prototype was converted from P-38E 41-1986 with modified tail booms, but was not fitted with floats. It did not enter production. P-38F: Production variant with inboard underwing racks for drop tanks or 2000 lb of bombs, 527 built P-38G: Production variant with modified radio equipment, 1082 built P-38H: Production variant capable of carrying 3200 lb of underwing bombs, improved intercooler design along with automatic oil radiator flaps, 601 built P-38J: This production variant was built in 1943 with improvements to each batch, notably an increase of Hp that came with an improved turbo charger. It also included chin radiators, flat bullet-proof windshields, power-boosted ailerons, and increased fuel capacity* 2970 were built. Some were modified to pathfinder configuration and to F-5C, F-5E, and F-5F. P-38K: With 1425 hp engines, larger Hamilton Standard Paddle-bladed propellers were added to compensate for increased power, one was built* a single P-38E was additionally converted to the same propeller as the P-38K. P-38L: With 1600 hp engines, 3923 were built, which included 113 built at Vultee* later conversions to pathfinders and F-5G were made. TP-38L: Two P-38Ls were converted as tandem-seated operational trainers. P-38M: Conversion of P-38L as a radar-equipped night-fighter F-4: Photo-reconnaissance variant of the P-38E, 99 built F-4A: Photo-reconnaissance variant of the P-38F, 20 built F-5A: Reconnaissance variant of the P-38G, 181 built F-5B: Reconnaissance variant of the P-38J, 200 were built, and four were later sent to the United States Navy as FO-1s. F-5C: Reconnaissance variant of