Ubik
1871
Hey Z
My 2010 doesn't have a lug mark either, I don't believe any of those refs do (although not that many to make an accurate sample)
I always assumed the lug number was to ensure that the caseback that was made for the watch, stayed with the watch throughout the production process. Perhaps these were so specialised they didn't feel the need to do that - absolute guess of course 
I think there might even have been 3 types of MP's - a thin, thick and concave.
What also intrigues me is that even thought Longines would use screw back cases for later 13zn's, they went back to the press back as early 30ch have them as well. A hidden history yet to be discovered?
Longines 13ZN Mushroom Pusher ref. 2191
I realized there isn't much articles and coverage on these illusive legends. I am not attempting to do one, but perhaps some appreciative photo journal on a recent acquisition. The best part of the watch is actually the case, no, dial, no, pushers (mushro...
When I googled "mushroom pusher" it didn't turn up watches
That watch has an awful lot going for it. I love the dial and the blued hands, particularly the small chrono minute hand with the barbs on the sides. The case and the mushroom pushers are killer. What's not to love about a vintage hand wind column wheel c...
Not at all! :)
The 13zn, being a superior movement, is easy to work on. Parts ain't awfully everywhere but they can be found and worse scenario, you can get them from cannibalized watch.
What a beauty!
I\'m very pleased you own this watch and you have shared it with us. Honestly one of the most beautiful chronograph I\'ve ever seen! Enjoy!
Indeed. This is one very charming old chronograph.
movement, case, dial, this watch seems to have it all.
Thank you for sharing your very nice watch
A well known piece among the 13ZN cognoscenti with a known provenance… Bravo! Longines were one of the few makes that experimented much with different types of water/ airtight case backs for their chronographs in the late 30's. This one is one of the most...
Hey Z!
Thank you for your comment and obviously you know your stuff! On the case number on the back of lugs, I have seen a few examples without that number too. Though far and few, I do think they exist but I do not know why. On the pushers, I do think they are ...
Hey Z
My 2010 doesn't have a lug mark either, I don't believe any of those refs do (although not that many to make an accurate sample) I always assumed the lug number was to ensure that the caseback that was made for the watch, stayed with the watch throughout ...
Hi Ubik,
Well, there is always an exception to confirm the rule... isn't there? ;-) I believe one of the refs actually has its case sub-number stamped on the back of on lug and on the inner case back, but it is the ref. that one does not see that too often. Yes, t...
Erratum...
Only one valid reference number for the MP's (mushroom pushers) Important to distinguish three things here: 1! Case ref number. That's were there is the most confusion… 2/ Internal batch number 3/ Possible case serial number within a batch. You can come t...
I'm really happy..
You finally got it J ! The 13ZN is also one of my grail watch, not this particular configuration, but I know, the step case with mushroom pusher is the grail for most. Congrats again, and wear it in best health ! Hope to be able to see it soon! Best, Sam
Wow! Great pics and helpful info...
I love this reference but to date I have never been able to pinpoint any specific information about it, so your post is very helpful. It's a wonderful watch; congratulations! Thanks for sharing! Cheers, Brandon
Oops, forgot to add
ref. 4270 is not a myth. It exists! I even have a copy of Longines original technical card with period picture for this ref. As you probably know there is an wonderfull little illustration in a 1936 Longines catalogue of a black dialed specimen of this re...
Well Rficul, you certainly know how to make a splash
What a wonderful 13zn. Wear it in good health.
Legendary movement
The 13zn is truly one of the best chronograph movement of all time... Wish Longines finds a way back to their glory days. The offerings now just dont feel the same anymore... At least to me.
I just love this watch the massive step case and mushroom pushers give it
a lot of flamboyance