Did the installer use a tool with a center stud to keep the top of the clamp from pyramiding?
Or did the installer use a tool missing this center and the top becomes a pyramid shape? A pair of diagonal cutters also makes this shape.
Is this an installer preference, tool used or factory? Or just random?
Many of the reproduction clamps (not all ) over the years were made with a small divot where the small depth post (for lack of a better tool could be seen. That feature on the tool or some tools used, does not move as you tighten the clamp and don't recall seeing a tool where that depth section is adjustable
I think you will find that its a year by year thing and in my experience the divot is not visible on early cars and haven't looked at later cars to see if this changed in the very late 60's or even the early. Know a fair number of people, including myself, that removed the divots from the reproductions to get them to look more like originals in the past.
Also for the purpose of this thread notice that examples I posted do not have the divots in the top of the pinch area from the tool.