All,
I was just PM'ing a member giving them a helping hand, and thought I would share this tidbit of knowledge in public as well.
This has been discussed before, but I figure the pictures will help.
The discussion is about What 1575 Rolex movement to transplant into a Yuki, Phong, even MBW with the LEAST amount of issues.
The short answer is you want a donor movement from a 150x Date or 1680, 1665, 551x to make life 'easiest'. (Beware eBay auctions with 1575 movements advertized as 1680/1675/551x as some are actually pulled from 160x DateJust's. Use the photos below for confirmation).
You CAN use 1575 out of a 160x Pie-Pan dialed DateJust, but you will want to swap the calendar retaining ring or GRIND it down.
Allow the pictures to explain.
Upper Left Rolex Package IS THE correct part. PN: 7956
This is the 1601 DateJust setup. Note the sloped shoulders.
Part 7956
Left is from 1601 Pie-Pan type dial, right is right!
See the Pie-Pan retaining ring is a larger diameter. You can grind it down 1mm as needed.
This is ready to slide flawlessly into my old Yuki.
To recap, there are 3 different Calendar retaining outer rings.
1.) For Pie-Pan dials found in 160x series Date Just (these have the sloping outside) (you don't want this, unless you do what I did. I swapped the part, or you can GRIND down outside shoulder.)
2.) 1675 GMT's had a flat version as well, but slightly different diameter. Ignore this since you probably won't find one of these.
3.) The one you want is the same across 150x, 1680, 1665, 551x. So a 1501 Date is the same as a 1680 if you are going for 1:1.
Hope this helps.