Cat 963B. Well, I think today is my lucky day. Yeah, I know I didn't drill the hole perfectly in the center...it was hard to get to. lol.
Those are the best extractors I have found. Those combined with a set of Snap On LH cobalt drill bits handle most situations. What is the diameter of that thread? Not as critical on the larger sizes to be exactly centered especially when the other side of the hole is open. You can always use the gas axe if the stud wont budge. A healthy dose of never sieze upon assembly will make it a lucky day for the next technician.
What brand of extractors are they?
Ridgid brand. Make a quality line of pipe threading equipment and tools as well.
It's an M20X2.5. I seemed to have great difficulty finding the center in large part because of how the bolt was broke off. Never sieze is SOP whenever I work on anything. I never understood why more people don't use it.
Just to say they were also marketed under the Blue Point line.