Hi Conslaw,
The long-nosed P-40s suffered with severe ground looping problems. NACA tested what were initially called leading edge scabs on 39-165 in summer 1940. Here's what they looked like:
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Despite the advantages of the NACA scabs, a simpler fitting was designed for the wing root. It was retro-fitted to existing long-nosed P-40s and Tomahawks, and added on the production line. Note the difference between the original fairing on #38 and the modified (but yet unpainted) fairing on #31.
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Hopefully this will answer your questions, but for more on the problems and mod, allow me to recommend my book on the long-nosed P-40s:
Amazon product ASIN 0985714948
Cheers,
Dana