Just my thoughts on the bridge question, but my very first vintage watch of note that I purchased was a Heuer Carrera with serial 56795 and polygonal case back. The watch was unusual in that it had a Heuer-Leonidas bridge, but appeared to never have been serviced and came from estate of the original owner to someone who didn't know watches that put it on eBay, so I don't think it was switched. It didn't come out of the dealer system of watches.

I think it is quite possible that the Heuer-Leonidas bridge is original as Heuer did not alway approach production in a direct serial number way, but the case may have been set aside and later finished with that bridge. These late production Autavias have different characteristics, including one we have seen with a "T" above "SWISS" in the hour register signaling tritium lume. The lume on that watch has a different and creamier look than the other versions with lume that appears to be radium in texture. Has anyone tested these watches with a Geiger counter?