[CJE]

However, I do believe that there are two designations that were taken the other way round by air historians hitherto and concern the FG-1 and FG-1A.

As far as I can ascertain, the FG-1 was a "denavalized" version earmarked for the USMC, while the FG-1A did have an arrester hook (but no folding wings or flottation devices).
This is the only reason why you can find FG1-As aboard US carriers in 1945 but no FG-1s.

If you look through the "A" suffixes of the BuAer, this specific case is mentionned with for example the SOC-3A, which indeed was a land-based aircraft equiped with an arrester hook.
And once again, the "A" suffix has nothing to see with the canopy.

All this leads me to believe that Green, Tillman, Bowman and many other renowned authors got it wrong: the F4U-1A never had any legal existence.
So many people can't be wrong but sometimes they are.

Veronico's explanation seems to have legs (see previous posts). However, at the time Vought's permission to distinguish its variant with the new canopy with an "A" suffix would have been granted, May 1944, the BuAer had already issued its exhaustive list for suffixes, excluding a change of canopy.