Chris, What's the P-51A or B clone with dive brakes on the wing top. It's name is Baby Carmen.
Phil, this is the short answer. When North American (NA) made the P-51A for the Brits, the Stupidhead American army didnt want it. But they ordered it as a dive bomber, the A-36 Apache.
That is what you see...there are only three left in the world. With a lousy supercharger, the Allison couldnt get the P-51A or the A-36 up to any fighting altitude.....
Then an American officer working with the Brits in England fitted a two stage two speed intercooled blown Rolls Royce Merlin to a P-51A and that became the B and C models
(the difference was the 2 NA factory designations)...and the rest is History. Oddly, Packard was already building the Merlin for the Brits as Henry Ford nixed his son's deal with the Brits
to build it. Packard made the Merlin assembly line friendly and supplied them to the brits and the Americans. For more visibility, NA put on a bubble canopy to make the D model which cost the
aircraft a few MPH but had great visibility. The Allison soldiered on in the P-38 with its GE turbo superchargers, the P-40, and the P-39 and P-63.
Oddly, in racing Mustangs, the Allison connecting rods are stronger than the Merlins so they put those into the race Merlins....
Also ironically, the Mustang was so fast due to a British invention....the Merideth effect Radiator that recovered IIRC 600 hp of drag due to its trick design.
Many think it was the laminar flow wing but according to the head designer, the Mustang never achieved true laminar flow....