I have been on the list since Feb. and there has = been alot of discussion and archives on the issue of the cause of leaking heads and = the type of coolant that is used. Has anyone looked at the type of water = you should use? I worked in a shop in State College, PA (Gemini Enterprises, = John Simbeck is the owner, one of the best mechanics you will ever meet) = while attending Penn State. He had me replace his 390 out of his '69 = Ford F-150 one day and told me to look for anything that needed replacing as = well. I took the radiator out and it looked brand new. I asked John if he had = replaced it recently and he said no, its the original rad.. I asked why it was in = such great shape and he said because he used only distilled water with the anti-freeze. He said the minerals in the tap or spring water causes corrosion in a cooling system. = Perhaps this is what I just saw on the head I saw tonight while replacing the = head gaskets. Based on John's testimony, I always use distilled water = in all my cooling systems and have never had a single problem. Just a thought.