old scalloped crown NOS reference 4203??

I came across a seller that has a scalloped stainless steel crown which he claims to have reference 4203 on old Omega catalogue
Have no idea what that means as I have found nothing like it anywhere on my searches

The other information he mentioned was that the crown measures
4.4mm in diameter
2.1mm from base of outer edge to top of dome
and should fit a case tube of 2.0mm
claiming it is for a 166.002, 165.002

It mentions no other 165.xxx or 166.xxx reference. Why would a 166.009 or even a 165.010 be excluded is beyond me ?

Has anyone ever come across to such data. The seller is 89 years old and wanted to check that he is still coherent ( without being judgmental) and if this information is consistent with with others as I did not want to pay an expensive premium with shipping costs and be stuck with something that would not be useful towards my timepieces? Thanks for any input!

Thank you for posting this!
Did this diagram also come with other information such as for what case reference numbers it is for?

W0W!!! this information is gold!!! Thank YOU!!!! I remember my old watchmaker ( now deceased) had a similar list which he always referenced, but I have never seen one online unless it has been previously posted here and I could have missed it in my searches.

The only problem is to interpret everything that is in French and investigate if this 4203 crown would also fit a 165,XXX case as it looks like the older thin scalloped crowns once used when the 14779 and 165.010 were first issued before the new reference being used today.
Hopefully I will see if the seller is telling me right information.

this is exactly the information where I got my uncertainty too!!!!. I have been studying those charts you posted very carefully and are a wonderful piece of information,


Correct!!! I noticed it from your posted images. I wonder if the 4203 is used in the model below as the 4205 protrudes more than the image shows ( the image is not mine nor is the watch and I have used it only for illustrative purposes only)!
The 4203 and the 4205 use the same case tube of 2.0mm, so I wonder if both would work here Thanks again for your further efforts in sharing the information