Reuben Craddock & Sons handcuffs

Help needed. I have acquired a pair of RCS handcuffs but they have different numbers stamped on them from any I have read in previous discussions. They have RCS with 739 stamped on the end of each barrel with what look like "y's" round the edge and on each hinge is the number 558.
Any ideas, anyone, please???

They all have different letters and numbers stamped on them, so I'm not sure what the question is???

Most seem to have a date stamp. Mine don't! How do I date them?