Forget my earlier post :
Dana Bell post from a coupla years ago ...
There's been some new research into Corsair colors. Records from the National Archives show that only the first 300 F4U-1Ds wore the four-tone camouflage; all of the FG-1Ds wore overall Glossy Sea Blue.
The only green versions of zinc chromate could be found in the cockpit - everything else was one or two coats of yellow (untinted) zinc chromate. When the cockpit switched to tinted zinc chromate, there would still be components (particularly seats and rudder pedals) in Dull Dark Green for some time. Eventually, everything went to Interior Green at some unspecified time in production. Fuselage sidewalls were painted black above the consoles late in FG-1D production, after Vought had switched to F4U-4 production. Vought had found a stock of aluminized zinc chromate - a very bright candy apple green primer - and received permission to use this up as a cockpit color; that stock was probably depleted by the time the F4U-1D went into production.
Wheel wells were normally painted GSB like the exterior, but at least one -1D carried a Light Gray finish coat.
What you would see inside the flap coves would be sections of the exterior skin that folded up as the flaps came down. The little I've seen of the fuselage skin above the flaps suggests the exterior color was used there. There would be no bulkhead forward of the flap cove; anything you might find there would be yellow zinc chromate.
Hope this helps!