It's Cook Cleland's FG-1D "Lucky Gallon" just prior to it being painted at the site of the Cleveland Air Races, 1946, with it showing up in just its base white paint. The F4U-1/FG-1D Corsairs had updraft carburetors, and what you see along the bottom of the cowling is a modification/addition of an extended induction trunk for the carburetor. A similar induction trunk was added to Cook Cleland's F2G Super Corsairs, which had downdraft carburetors, and thus the trunks on those were atop the cowling.
More photos and info on this aircraft can be seen here:
http://f4ucorsair.freeforums.org/rare-u ... -t184.htmlhttp://www.fsxairsports.com/smforum/ind ... topic=34.0