I do not think it is broke but maybe part of a 2 piece. Hard to see.I followed your advice and biked along the old west shore RR (now a bike path), and found 4 insulators. From left to right: hemingray 42 hemingray 19 hemingray 19.
I don't know about the right most one. The top is broke off. I apologize if this is obvious I am quite new to insulators.View attachment 207593View attachment 207592View attachment 207594