I read this thread a while ago on Custom Cockers about earlier STO Autocockers Serial numbers stamped on the back blocks that had the line milling from the body continue onto them. Supposedly the two digits stamped onto the back blocks match the body they were serialized for.
http://customcockers.com/forum/showthread.php?45579-STO-history-lesson-please
No one had a picture of the back block next to the serial in the thread so I took one of this STO broken down. Serial is “31064” and back block is stamped “64.”
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