Or, you can use a hole saw and drill a hole through the firewall and remove and install the plug, then put a plastic hole plug in there. But this is from many years ago when ebodies only cost 500 bucks and dart/dusters were free. Pulling the heads is your best bet. If they rotted out, you may want to have the machine shop re work them. If you can manage to knock out some of the easier block plugs, your engine will probably like it better and run cooler this sumer, by flushing out the sludge....ALAN