As part of the deal the USAAF was to get a small number of the British order for test and evaluation purposes. The great drawback to the original P-51 design was thew original Allison engine. If you look in the dictionary under dog there is a pic of an Allison V-12:-).
The USAAF did not have any funds in 1940 for fighters as the P-38, P-39 and P-40 had the bulk of the money tied up. They did have funds for dive bombers so to keep the P-51 going it became the A-36 Apache and as a dive bomber the A-36 was not.
Much has been made of the British deciding to see what would happen to the Mustang airframe if a Merlin was added. I have seen some artivles that the USAAF/NAA was also looking at the Merlin in about the same time frame. Any ways with the Merlin engine the P-51 became the best fighter of the second half of WW-II IMHO.
A few Mustang pics for the P-51 fans, yee haw!!!
And an A-36 pic, showing the dive brakes fitted to the P-51.
Regards
alfa6
I remember going to the Reno Air Races back around 1990 or so, the most distinctive sound was the one coming from the P-51 as it flew by on the deck with full boost and injection at I think something like 470mph. Full race configuration was a bit faster than its war attire naturally. After that was the Bearcats.