Still on ther quest for the pace mint vendor cover lock. Unfortunately the lock from Sam didn't work. So I have some more pics to see if it helps. Thanks
Try looking on ebay and look for national locks...look under various headings as well. Dont think mine is original but that looks similar to my lock on my Mills Fok and its a national.
Had the same problem. That is a Yale # 256 cash box lock (box lock) according to their 1928 catalogue. Not made by anyone now. I finally bought 2 from a bandit on ebay.