Interesting I never heard of P-51 G and J models. As far as I know in the
F was used in wording for tactical reconnaissance role. (F-6)
There was XP-51F, XP-51G and XP-51J. An XP-51F (one of three built) with the three-bladed Aeroproducts propeller unit The lightweight Mustangs had an all-new wing design. The wing airfoils were switched to the NACA 66,2-(1.8)15.5 a=.6 at the root and the NACA NACA 66,2-(1.8)12 a=.6 at the tip. These airfoils were designed to give more low-drag laminar flow than the previous NAA/NACA 45-100 airfoils. In addition, the wing planform was a simple trapezoid, with no leading extension in the wing root region. In 1943, North American submitted a proposal to redesign the P-51D as model NA-105, which was accepted by the USAAF. Modifications included changes to the cowling, a simplified undercarriage with smaller wheels and disc brakes, and a larger canopy and an armament of four .50 Brownings. In total the design was some 1,600 pounds lighter than the P-51D. In test flights the XP-51F achieved 491 mph (790 km/h) at 21,000 feet. The designation XP-51F was assigned to prototypes powered with V-1650 engines (a small number of XP-51Fs were passed to the British as the Mustang V), and XP-51G to those with reverse lend/lease Merlin RM 14 SM engines. A third lightweight prototype powered by an Allison V-1710-119 engine was added to the development program. This aircraft was designated XP-51J. Since the engine was insufficiently developed, the XP-51J was loaned to Allison for engine development. None of these experimental lightweights went into production.From 1947, the newly formed USAF Strategic Air Command employed Mustangs alongside F-6 Mustangs and F-82 Twin Mustangs, due to their range capabilities. In 1948, the designation P-51 (P for pursuit) was changed to F-51 (F for fighter), and the existing F designator for photographic reconnaissance aircraft was dropped because of a new designation scheme throughout the USAF. Aircraft still in service in the USAF or Air National Guard (ANG) when the system was changed included: F-51B, F-51D, F-51K, RF-51D (formerly F-6D), RF-51K (formerly F-6K), and TRF-51D (two-seat trainer conversions of F-6Ds). Quote; 'Ultimate Mustang? Hell, it would have just spanked any piston fighter of WWII' - well production version with guns etc and equipment is different to protypes and test models. I don't think it would have been any so much better than some of the other ultimate WW2 fighters just my opinion and after all in here say: quite a few manufacturers, test pilots and nations at the end of the war all have what they believe is ultimate, depends on who's opinion - spanked!
More Corsair, Spitfire & Ta152 fan than those ponies!
Still
interesting request on a nice plane.
Still like to see the P-51
H which was a production fighter although some P-51Hs were issued to operational units, none saw combat in World War II, and in postwar service, most were issued to reserve units. The P-51H was not used for combat in the Korean War despite its improved handling characteristics, since the P-51D was available in much larger numbers and was a proven commodity. Cheers