My 1952 (New York) Bach came with a 10-3/4CW mouthpiece. After several years it got a little pitted and I bought another one. The newer one is marked "Mt. Vernon" and cost $7, so it was a long time ago. The newer mouthpiece looks like I would expect a wide rim to look: bigger, more rounded rim, and about 1/16" larger outside diameter (although the cups look the same).. I didn't like it much at the time, so bought a 7C and used that until I hung it up in 1972. After 40 years, I've started trying to play again, and awakened my curiosity about the 10-3/4CW's. Was the first one mismarked, or was the design changed? By the way, at 77 years, I'm finding the wide rim more comfortable.
Dick