[Jordan Baker]

I wonder if there had been a production change along the way. I know that mine uses counter sunk screws pushed in from the bottom. The backing ring that fits on the inside of the roof has all the holes countersunk.

Great site Rob. They have quite the collection. I don't mind the zinc as it helps keeps the threads rust free longer. A few years ago I made up a plate to hol a pile of fasteners so I can sandblast off the zinc from the head. Then spray self etch primer all without having them fall over. Works great.