You guys that know 6.2's well probably aready know this but for the rest of us, a mushroomed glow plug can be removed without any special tools or removing the head. Just got the one I had out, its the first thing that has gone right so far. Remove the injector and unscrew the glow plug, then grab the glow plug with vise grips and bend it back and forth until it breaks off. Then use some hemostats or spring loaded tweezers to grab the end of the glow plug and pull it through its hole inside the prechamber. Twist it up and out. Not much space to work but it beats the hell out of removing a head!!