Merchant Automotive 2001-2021 Duramax Glow Plug Removal Tool Adapter and Socket – 10473
These tools combined with an air hammer provide the hammering effect needed to loosen a stubborn glow plug. The flats on the bit provide the ability to use a wrench and apply the needed twisting force. Some machine work to the socket takes place in house to make sure it does not damage the Duramax glow plugs.
Using an impact wrench rather than this setup often just twist off the glow plug rather than breaking it loose.