Very similar one(s) here. Not exact same size. Maybe they would welcome a pic of one with your dimensions.
CD 315-334 (Umbrella type high tension - One pice) (allinsulators.com)
Whoa, Rick. Another cool thread I missed. I really should have subscribed to this subforum earlier so I would get notices.
Was these projects you were working on? What's in the last picture?
Remember when people talked about Earth being a big blue marble?
Apparently the big blue marble has a giant steelie in the middle. Trippy.
https://www.cnn.com/2024/07/05/science/earth-inner-core-rotation-slowdown-cycle-scn/index.html
Alley stopped making marbles in the 1940's. Champion kept making marbles into the modern era. My belief is that it was easier for errors to get past quality control in the modern era. Fewer kids playing marbles. Less important to get them all round.