Odd Chain Links on a Darby

Has anyone ever seen a Darby set up like this one? Can anyone tell me anything about it or its history? It looks to be a fairly early model by looking at the way the cuffs are made. I havent seen the stamping on them yet. These are on their way to me. I acquired them in a live auction from Australia this past weekend. I could swear I have seen members on here post pics of similar cuffs before, but i have searched and searched the pages of the forum and have come up dry. Anyone out there have one like this set? Im curious to know where these modified by a prison or jail in Australia to better fit their intended use? I wouldnt think Hiatt would had offered them like this from the factory? Any insight is appreciated. Thanks for looking!
-Richard Knip-

I’ve never seen a Darby cuff like it. Congratulations! Ron J

Similar but different

Great set of cuffs, Mark!
-Richard Knip-