3 notch case back on a IWC 35mm?

Hi all, I have not been on here for quite a few years, so many so  I had to re register.

I have owed this watch many years but am a bit perplexed at the case back having 3 notches, it is something I have never seen on another IWC.

Here are some detailed photos. The dial is very nice with light aging but like the hands and movement all very clean and tidy.

The watch is around 35/36mm across. I have sent a message with detailed photos to  David Seyffer at IWC hoping to get a response but thought I would ask here too.

Thanks, Michael 

Nice Caliber 83!

Is the caseback snap-on or screw-down. 

It may be a hermetic case?

Hi Mark!

The case back is screw down.

The original lead seal is still in place too.

Thanks, Michael 

Thank you

So that explains the three slots for a caseback spanner. 

It does Mark, yes 👍 

I want to know if anyone has one or has seen another 3 notch case back really or maybe find a reference number. After plenty of research I came up with nothing.

Thanks, Michael 

Very cool piece, I would love to hear what David is able to tell you. 

Here is part of the kind reply from David….

“This is indeed a very interesting timepiece. According to our records, this watch was sold to Slovakia in 1943.

It was likely originally delivered with a leather strap.

Unfortunately, due to the absence of a specific reference in our case records, we are unable to provide further definitive information at this time.”

He did mention he had never seen a three notch case back before and was also interested in what you guys on the forum thought.

Many thanks, Michael 

I think from memory mr.kolesa owns a couple of examples...if he is still around.

Plenty of smaller size 3notch examples still about..less of this highlighted size..with direct correlation to less of that size case ( late '30's)

You may find some samples with four notches, or even one or two with two notches, which sort of spells out the shenanigans of the period.

* forum wont let me edited for some reason