Swiss F1 driver Jo Siffert was synonymous with Heuer back in the 1970s, with the Autavia that he wore now widely known as the "Siffert Autavia". Of course, it was never called this oficially, it's just a nickname given by collectors

But there has been an official Siffert-branded TAG Heuer- this S/el with Jo's signature

And there was going to be a second-official model, but this prototype below made it into production without Jo's name

 

All Chronomatics are Calibre 11s, but not all Calibre 11s are Chronomatic! Only the very first series of watches in 1969 used the Chronomatic branding, and we then have a couple of years of regular Calibre 11 production (including a modified Calibre 11 called Calibre 11-I) before the Calibre 12s came on stream

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