J.J.& A Racing makes the perfect tool for it. i bought one cause i had 3 swollen stuck plugs and the way theyr tool works makes it a breeze. its well worth the $100 in my book.
google " J.J.& A Racing glow plug removal tool"
basically you unthread the glow plug slip the tool onto the glow plug and it apply s even outward pulling pressure to it. the glow plug dosent turn the tool dose.
This car is 100% death proof. Only to get the benefit of it, honey, you REALLY need to be sitting in my seat.
(1987 GMC jimmy v1500 120k on the clock)