Jon_a_its:
Nomclementure doesn't usually include dashes, eg M1, M48, P51 etc
so I did a search for P51, & .... nada....
maybe you broke it?
Actually USAAC, USAAF, and USAF aircraft nomenclature usually includes the dashes. The US Army ground vehicle stuff does not. A Mustang in the P-51. And an Abrams is the M1.