5.2 Magnum Spark Plug Heat Shields

What is the easiest way to remove the 5.2 Magnum Spark Plug Heat Shields. They have rusted to the heads and i cannot fit a socket inside. (7 years and 56k miles since plugs were changed) I used the vise grips twisting and hammer method which took 2 hours. How have yous done this before? I have tried to repeatedly get sockets on and all else fails to the spark plug breaking and having to yank the heat shield. Any ideas or tips? I got cylinders 1, 2, 4, 6, 8 done. 3, 5, and 7 are giving me problems.