Yes, you are correct about those to also. While the F4U4 Corsairs used in Korea were single engine, they were also the last piston engined aircraft to be used in wartime by the Marines if my memory does not fail me. The Navy also introduced the F9 (twin engine) during that time though I don't recall them seeing any combat.
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If you are referring to the F9F Panther, then you are correct, it is powered by 2 Rolls Royces, and it did see combat..my Grandfather flew them with VF-781. The Navy was also flying the A1 Skyraider well into Vietnam which was Piston, though I also dont recall any use of them by the Marines.