The North American NA-68 was a development by the North American Aviation Company of a simple single seat, low-wing, single engine fighter for export. The design was developed from the basic model NA-16 training aircraft of 1935.


In 1940, the Royal Thai Air Force ordered six aircraft designated NA-68. These aircraft were en route to Thailand when seized and returned to the United States where they were disarmed, assigned the P-64 designator and used for advanced fighter training.


Another single seat fighter that evolved from the basic NA-16 trainer design is the Australian Commonwealth Aircraft Corporation CA-12 Boomerang fighter.


Source:
Info: Wikipedia
http://en.wikipedia.org/wiki/North_American_P-64
Profile: Fighters of The United States Air Force
Published by Temple Press/Aerospace