Ford used the cork gaskets originally. Our cork gaskets are a cork/neoprene blend and are what I recommend using. We also offer a neoprene gasket for those who prefer it instead.
Both kits contain a thin blue colored gasket. Use that as a slip ring between the gauge and the outer nut if you aren't going to use the original brass slip ring (A-9331) If you are using the A-9331 brass slip ring, disregard the blue gasket in the kit. U.S.A.