After checking (in my dreams)... the VTOL PB51 was the PB51E-1 (built by Edo Aircraft), and it is still top secret, alas.
But I have a friend of mine working in Washington (he is the boss of something, I don't know which office exactly) [he is a black man with an Irish name: Barak O'Bama], and he signed the paper nicely for me to present it. Here it is: