The Yashikor are 3 elements and the Yashinon are 4 element I believe, I have the info saved somewhere just can not find it. I have the A model which I like a lot and wish I could afford this one, the 635 has been on my wish list for a long time.
“In the end, it's not going to matter how many breaths you took,
but how many moments took your breath away.”
― Shing Xiong
There are many Yasikor lenses that are 4 element, Yashica switched some where in the middle of the production without renaming them. They later switched design slightly and renamed the lenses as Yashinons. I have owned Yashica D's with all three variants and after stopping down a couple of steps, are almost undistinguishable between them. I have also had the LM modle with a 4 element Yashikor and it was a good performer.
BTW: the big kid in my avatar is my hero, my son, who proudly serves us in the Navy. "SALUTE"
The 35mm adapter seems to be a Rolleikin, made by Rolleiflex. I had one in the 1950s and it worked very well. It produced 35mm in a "portrait" mode and of course I could sync with strobe a 1/500 sec. which most 35mm cameras could not do at the time.
You are probably right. I don't know where I got it (some box lot at an auction, most likely), but it worked in the 635! Lucky for me! I would have hated trying to find the Yashica spool just to complete the kit!