Chevyboy?? You can get similar tools currently that do the same thing for SBC's using aftermarket nuts on the rocker balls...a tool like this holds a square drive socket for the locknut and in the middle has a bit of whatever sort in the middle. Actually, I think that's backwards for SBC...the socket part adjusts the nut over the ball or pivot, the inner piece is usually an Allen wrench for a lock screw in middle. Reduces the number of hands you need when running the valves.
Older ones like this would be used on a screw and lock at tip of rocker arms. Similar idea but pre-ball pivot/center pivot adjustment for shaft type rockers.