[CJE]

Thanks Frank.

I eventually found out the answer.

See the attached scan from the book "F4U Corsair" by Nicholas A. Veronico et al, Motorbooks, 1994.
In fact, the designation F4U-1A was only officially approved in May 1944. But at that time, Vought was building F4U-1Ds, Goodyear FG-1Ds and Brewster had gone out of business.
Thus, not a single F4U-1/FG-1/F3A-1 with bubble canopy ever sported the suffix "A" on the rudder.

That settles the matter once and for all.

Thanks to all.

Chris