OK, thought I could take it out with an "easy out". Now I've got a broken easy out in the hole I drilled in the broken bolt. Can't drill it as drill won't bite into the easy out material. So I have watched several you tube videos with an electric welder building up the bolt and using a vice grips to get it out. The heating of the bolt and the aluminum block acting as a heat sink helps break the bolt loose. Has anyone tried this? Or just forget about it and hope the other bolts and gasket will seal up the exhaust without this last bolt holding anything.