We are not Willys experts but as best we can tell, this is a new old stock Willys and Jeep fuel/gas cap # 640594 in the original box. This N.O.S. cap is painted black and looks to have never been installed. This cap is heavy and not a cheap replacement. Fits a filler pipe approximately 1-7/8” ID and about 2-1/4” to 2-1/2” OD. There is a loop on the underside to possibly accept a chain or cable so you don’t lose the cap?

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