P-51's in movie "Empire of the Sun"

Well, since it's the Navy, and they couldn'b be like abyone else, it's
one of those "That Depends" things again.

For example, the Amphibian models of the PBY and PBM flying boats were
the PBY-5A and the PBM-5A.

But the F4U-1 Corsair with the bulged canopy was an F4U-1A.
(And the version with 4 cannons was an F4U-1D).

But weren't the letters A, B, C. D, assigned in alphabetical order, to
successive mods?

An uprated engine was usually signified by an 'F' tacked on, but not
always.

Even if the preceding mod was an A or a B? Are you saying the Navy
jumped over the C, D, and E? What if the preceding mod was up to G,
or H; did they go back to F?

But it wasn't always consistant. An F6F-5E was a Night Fighter,

Was that not because the preceding mod was the F6F-5D?

and an PBM-3E was an ASW Patrol Bomber.

And did that follow the PBM-3D?

Thanks. vince norris