Researching 1968 IWC ref. R810a. buckle. Help!

Hello all, thanks in advance for your insight, assistance, and patience with my plea for help. I just acquired a gorgeous 18k NOS 1968 IWC ref. R810a from Goldammer and I'm trying to ascertain what the original buckle looked like and possibly purchase one, or at least something close to it's design. Any assistance would be greatly appreciated. This is my first foray into IWC and I'm at a loss. Thanks again and take care!!

It is IWC "Unroc" buckle, and looks like this:

Thank you very much for the help. Much appreciated.. Take care!