I've noticed that on many FAA Corsairs in EIF markings that the entire cowl flaps, including the top ones, are operable. These aircraft lack the blanking plate fitted to prevent oil leaks and smearing on the windscreen. This can be seen on the following videos:
https://youtu.be/KM1PvJwQmcE
https://youtu.be/-XKdaKadgNg
Does anyone know if this was a field unit-level modification, or only done at MU level? It is not lacking on BPF Corsairs (that I have seen).