What is this abandoned aircraft in Thailand?
Curtiss C-46 Commando
First flight was 26 March 1940. 3,181 were built. The one you have was stored at Don Muang, and ended up in Chonburi, Thailand.
Identifying features are the nose light, the now faded blue/gray cheatline that turns upward behind the cockpit windows, the black antenna under the cockpit, and the white paint under the nose that is gone from the belly:
(airliners.net)
Matching engine:
(wikimedia.org)
Matching front view:
(wikimedia.org)