A development of the BT-9/BT-14, the AT-6 Texan was the most
      extensively used trainer of all time with more than 17,000 built.
      The North American NA-26 was developed as a Basic Combat trainer
      and originally designated the BC-1.  The prototype BC-1 first
      flew in 1937.   A change of role to advanced trainer saw a new
      designation--the AT-6 in 1940.
      AT-6's sold to the United Kingdom, New Zealand and Canada were named
      the Harvard.  The U.S. Navy designated this trainer the SNJ. 
      Australian AT-6s built under license by CAC were called the Wirraway.
      Beginning in 1949, the U.S. Air Force began a program to re-manufacture
      existing AT-6 airframes.  These reconditioned and updated aircraft
      received new serial numbers and were designated the T-6.