273 rockers arm lock kit

Just get locknuts. That's my plan, I bought some from a member here. I have the factory adjusters, will give the rockers a flat spot with a file for locknuts to tighten on evenly.
Crane(bought out by Comp Cams) used to make them, there seems to be limited mfg of these for some reason.
PRW makes them, but not for factory adjustables.
What is the thread size for factory style rockers?