Well, you've posted what would have been my opening guess Jeff, a Rolex 6238 Cosmograph. I don't think I've ever seen the predecessor 6234 with contrast subs, but I'm no Rolex expert.

The 6238 definitely predates the Autavia by a few years, but there's a but coming... early ones seem to have uniformly coloured dials. And Autavias had contrast dials right off the bat. So it could be a close run thing, but my gut feel leans towards the Cosmograph having them before the Autavia went on sale.

But then I believe the Navitimer predates the Cosmograph too, dating back to 1952. Did it have contrast dials at launch? I think the earliest Navitimers are solid colours too.

So a complex question you've posed. It's not a case of saying when model X was introduced but instead of when it adopted contrast registers and that's a whole lot harder to find out...

And then we find out an obscure watch by an equally obscure manufacturer trumps them all by 30 years anyway...