Research has uncovered the below. But I don't know if I can see the "post 1967 flattened hex top nut" does anyone have an example of a pre-1967 non-flattened top nut other than the catalogs? And were all top nuts from 1967 on the same? I have a top nut that has lines inbetween the campagnolo --- Patent (like that but continuous) it looks older is it non record? What I take from this is that officially the inset type appear in 1969 and that the characteristic that makes it pre-1972 is the <c>? That seems odd since the type appear inset in the 1967 catalog... does anyone have an example of a 1967-69 headset?

This from Robert S. Broderick's Wool Jersey Album:

"chrome plated steel - post 1967 flattened hex top nut - post 1969 and pre 1972 with channel inset marked "BREV. CAMPAGNOLO ITALY BREV. CAMPAGNOLO ITALY" on upper cup and "BREV. CAMPAGNOLO ITALY BREV. CAMPAGNOLO <C>" on lower cup - caged ball bearings - model 1039"