The AT-6 Advanced Trainer. Twin-seat Army Air Force and then Air Force trainer used to prepare the majority of US pilots in WWII. Also used by Britain, Australia and Canada and the US Navy. Called the Texan (USAAF), Harvard (RAF), Yale, I-Bird, Mosquito, Wirraway (Australia), T-6 and SNJ (USN). Saw combat in British Air Force. The AT-6 was used in the Korean War, too, as a forward observer plane, spotting and marking targets.
This postcard was mailed 1 July 1944 from Aloe air Field in Texas by a pilot in training ("this is the plane I'm flying now, it's a pretty nice little ship")