FWIW Chuck Engle's picture posted by Tim S is the correct picture of a Revson spoilerr. John Buckman's picture is accurate as well. No brake ducts.
Chuck (Rocky) the flat spoiler is not a Revson spoiler. But it copies De Tomaso's earliest spoiler (mid to late 1970s), the one which preceded the better known GTS spoiler (in your second picture) which was a 1980s thing. In a catalog of "unobtrusive narrow body spoilers" I think one should also include the Amerisport spoiler, such as the one mounted on 6018.
I've been thinking about having this one modified so there's no "cut-out" for the grill in the middle, just a flat spoiler all the way across. Are you reading this Kirk?
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-G