New Years Puzzle

[Duggy009]

I know the answer
A very rare P-51 ???

Have fun.

[DB2]

Mustang Mk X, AM121

[Mark Allen M]

Mustang Mk X, AM121

"Delivered as an Alison engined Mk I Mustang to the RAF, converted to Mk X by the installation of a two stage RR Merlin 61 engine.
This aircraft arrived at the Rolls-Royce Flight Test Establishment at Hucknall on 7 June 1942 and was the first to be delivered but the last to be converted. A broader chord fin was installed but the aircraft was not slated for testing at Hucknall and instead was sent to RAF Duxford before being loaned to the 8th Fighter Command USAAF at Bovingdon along with fellow Mk X conversion AL963".

http://www.americanairmuseum.com/aircraft/20041

[Duggy009]

First time I have seen one in US markings.
A shame none survived.