367-3056 aka 3054840, 3673056 is a double feed Widia Metcut indexable 9/16-18 #6 (.375″od) SAE J1926 /MS16142 port contour cutter.  .509″small dia .979″spot face dia, .614″ bore length, 2″ head length x 3/4″ weldon shank. Predrill .41″x.875″.  2 effective flutes.

It uses standard c-187-bd/or c187-cc unhoned inserts along with j-312-ff unhoned or j312-fe/gf inserts.