Yes, it's official. Not at home at the moment, but can probably provide BuNo's if needed.
F4U-1 - "birdcage canopy",
http://www.largescaleplanes.com/arti...s/canopy04.jpg
F4U-1A - canopy with two braces over head,
http://hsfeatures.com/features04/ima...U-1A_tb_49.jpg
F4U-1C - Four 20mm cannons
F4U-1D - canopy without braces,
http://www.mobisux.com/album/data/50...air-canopy.jpg
FG-1
FG-1A
FG-1D
Mike