1/4 inch sockets, a swivel are useful tools. Be Careful when removing the glow plugs. DO NOT USE EXCESSIVE FORCE TO REMOVE THEM. (1/4 inch drive should give you plenty of leverage No extension like a breaker bar) Use plenty of PB Blaster to loosen them. Give the PB Blaster time to soak.
You don't want to end up like this:
http://www.peachparts.com/Wikka/BrokenGlowPlug