[Mr70]

I believe the notches in the snorkle was what they were using throughout 69-72 production,and possibly available for a few years afterwards..It's possible there was more then one manufacturer of these and one had a slightly different design then the other.
Your's sounds like a later Gm designed licensed piece to me that is not exactly true in detail to the original design.

I should explain that when I say repop,to me that means a later on manufactured piece,(GM licensed or not),that has lost some of it's original details during translation,to the original part once used on the assembly line.
I understand if others don't classify them that way.