Let me tell you about battling a C4 pan leak first hand !! I resealed mine 5 different ways before I got it to quit leaking. I tried a synthetic gasket dry and then with sealant, cork dry and with sealant, still the sucker leaked. I talked to a hot rod buddy and he told me to make a thick cork gasket, take yellow weather stripping cement. stick the gasket to the pan side and let set for a day. I took it further, I put a weight on top of the pan and pressed the gasket there for a week. Set nice and flat and permanent, like iron. Then I took black RTV and applied to the other side of the gasket and the tranny casting, bolted up right away(because I tried to let tack up and quess what, it leaked... snugged up the pan and let set for another several days.....No leaks !!!! END OF STORY !!!!