Interesting Siffert…Serial 339xxx

The current case serial ref 339xxx is very high for a 1163 Autavia. It is also super clean and sharp – I wonder if it was a case swapped at TAG HQ during service(?)

Never having seen such a high serial’d 1163 I spent some time googling and cross-referencing on the web.
I’ve only managed to find 3 Autavias in that range; 1 x Viceroy for sale by BdV a few years back, 1 x Cal 15 Skipper (on the OTD skipper page), and of course this Siffert.

Anyone seen any others at all?
Were 339xxx Autavias ever sold as factory builds or could it be that these cases have been issued/reserved only for service replacement etc.?
The number range doesn’t really fit with 1163s in the Heuer timeline.

I might try to source the correct case for this version – anyone have a spare one lying around in this serial range, please give me a shout – 224xxx; 241xxx; 242xxx; 243xxx 🙂
Or, maybe I should just leave as-is(?)