Originally they were made by Magistroni and the later ones were Campagnolo. They do not interchange except with a lot of grunting and groaning. My 1970 TEAM has a headset which is 1/2 and 1/2 with the Campy inner race ground to fit. The inner races are separate parts from the lug portion if you have never seen one apart,I think many headsets used this sort of system then it went to the more common style headsets . Things have now come full circle but I beleive the bearing cartridges just fit into the frame
BOB FREITAS
super Sunny day in NAPA CA USA