There were short and long-tail P-40K's and M's too.
One thing I should correct about my last post, is that The Fighter Collection's late-model P-40F is actually a rebuild, not a conversion. I was going off of a memory that I had in which it was incorrectly reported early on that they had taken an existing P-40 airframe and converted it to a P-40F, but I found a conversation with one of the individuals that were involved with that project that stated that it was really a complete rebuild.
Thanks again for the info. I was down at Duxford a couple of weeks ago, mainly to see the recently acquired BAe 146 and the restored Victor B.1, but of course I also had a long wander round the Fighter Collection's hangar.