Correct, P51 as in the WW2 fighter plane, and my favorite airplane of all time, and C for Cobra. I borrowed the idea from a local '66 Hertz Shelby owner who had the tag P51H. When I chose C, I didn't know that there was an actual version of the plane with that same designation, it was the razorback version of the more well-known P51D, the bubble canopy version. The conversations generally started are from aircraft fans who are happy that they got it, or think it was clever to put it on a Mustang car.