You have found four watches, including your own, with incorrect markings on the caseback. Three of them seem to have heavily brushed casebacks - possibly to try to remove the obvious incorrect "automatic" marking. The reason they all have Heuer on the dial is that it is the only brand of the ones you mentioned that will effect the monetary value when putting together a franken watch.

Sorry Hermann, others might agree with you, but you won't convince me.

: Mathis, thank you very much for your reply.

: Interesting discussion, thanks for that.

: Please have a look at the pics of some of the others I found with
: the exact same caseback style attached at the end of this post.

: I really don´t think that all these watches are put together.

: Because - and this observation is a really important one when we
: discuss this:

: I can not find any other 7765 OR 7750 chronograph with the second
: caseback variation (13/1) except the ones from Heuer.

: This is a very important point - which should not be overseen when
: discussing the 13-1.

: I can find a ton of the other variation (13 1), which has been used
: by a lot of other brands.
: I showed some examples of that in my other post.

: But, again, there are no other examples for the 13/1 except the one
: from Heuer.

: Which brings me back to this:

: It looks like the Ref. 13-1 had at least 2 caseback executions
: (first: 13 1 and second: 13/1).

: I am looking forward to read some more opinions on this topic.

: Thank you very much for your help.

: Hermann

: