North American XP-51J
The XP-51J combined a lengthened fuselage, as seen in the P-51H, with an experimental Allison V-1710-119 engine. This engine was not yet reliable and so the XP-51J did not live up to its potential. However, the experience gained with the new engine was not wasted, as later versions of the basic design were used to power the F-82E Twin Mustang (and all later models).
How to cite this article:
Rickard, J (7 June 2007), North American XP-51J, http://www.historyofwar.org/articles/weapons_XP-51J.html