My mistake. Typo. Ref. 7175 is correct.
BTW, here is a website just loaded with information on watches with the cal 30L and its derivatives.
https://longines30l.com/wordpress/
You might want to drop the owner an email and see what he has to say. He might know more than the Longines museum.
From what I can see, there were some gold-capped cases. All seem to be from the Longines Flagship model line.
gatorcpa
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