Jeff, I am curious if you know what role Sinn played in the development of the Heuer 510.543? Specifically, my Sinn 157 (rebadged as Bell & Ross Space Two) has the exact same case, with the exception of the collars on the pushers, as the Heuer 510.543….the early Sinn 157s had the EXACT same case (sans collars). Here are a couple of links to pics showing the older case I reference above (I did not want to use others pics without permission so I am simply posting the link).

http://forums.timezone.com/index.php?t=msg&goto=2213870&rid=300#msg_2213870

By the way, my watch pictured below is a titanium case, but I have noticed that the stainless steel cases are identical. I will post addtl pics, including side views, very soon.

I am very curious about this apparent relationship between Sinn and Heuer?
Lou