Those old top-breaks were the beginning of my education. Never saw a hammerless model in my youth, but those guns were plentiful.
Most were not marked and were sold through hardware dealers or other outlets, often times as promotional items. Many were made by Marlin that I know of, also many imports from Spain and Belgium.
They were bought used from second hand stores or junk shops. We had no idea they were dangerous to shoot and fixed them up and shot them anyway. My wife says I had a guardian angel.