Originally Posted by 05CrewDually
Pneumatic impact gun in short bursts. Or electric impact gun should do the trick.
Yeah, I've used this method several times. Variable speed impact gun with just a light "thump, thump, thump" on the plug. This is probably the anode plug if it's a Suburban unit. As previously mention, PB Blaster works well for penetrating oil or if that fails, Kano Kroil. If it's a 2006, it'll need a new anode rod. I also hit the threaded area with a bit of emery cloth to clean up the threads.
For cleaning out the unit, I use a small 3/8 diameter clear silicon hose attached to a shop vac. Rinse with water, then vacuum out all the crud. I usually do this each year when winterizing, just so the unit is all ready for the next year.
2008 Toy Tundra DC 5.7L Bagged w/LTs
2012 Windjammer 3001W, Atriumed