Chuck,
The silver M63 that's up on eBay has the front brake operated by the right lever! Neat, I didn't notice that...
I double checked and the BB lockring is normal/thin, and has 1 HS washer. BUT, I also have an original M61 (blue) with about 100 miles, from the same batch of bikes that the M63 is from, and it has a thick (4mm) BB lockring and 2 HS washers, (no black oxide frt der hardware though). So, On the face of it, it looks like bikes with 2 HS washers had thick BB lockrings, but this is a casual, broad brush observation.
John Barron
Minneapolis