It's very very interesting that you posted info about crystal manuals
I'm about to put up for sale (I normally don't promote my stuff here) a
searchable PDF of the GS crystal manual. I have scanned it in very HIGH resolution so that you can really zoom in on a page. You know how hard it is to read these things. My optical character recognition software did a fantastic job on this manual. It's easy to search on "Gruen" or "415/863".
You beat me to the punch on posting info on the book. I was going to tell everyone how helpful they may be in figuring out the model name of your watch
Sounds like I need to get on the ball and get it listed. I have scanned completely the #60 version and am including the index from #65. I just picked up a couple more and have several in the mail coming to me.
I have always had a difficult time reading the physical manual so I was looking forward to the scanned version. Check out these pictures so you can see how nice it is to be able to actually see the print

Here's your typical looking page
Page 29.jpg
And this is the level of detail I was able to get with a high quality scan (not the highest setting, but at some point it gets useless to go bigger).
Warning, this closeup is 2.8 MB. This is what my OCR engine was given to work with
Page 29 crop.jpg
About the 835/74 problem. What I noticed in these particular versions is that for some models, you MUST have the model name of the watch. There isn't a nice key that I've found yet sadly

that tells you the model name AND the size numbers. I'm attempting to help with that and other crystal size questions by making a searchable PDF. Do you happen to know the model names of the watches you are searching for?
A quick note about selling these and other reference materials... it actually takes me a long time to put something like this together. I'm not making a mint by any means and am essentially looking for SOME level of compensation for my time

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