C&I riveted bracelets did not come with numbered end links AFAIK. Swiss #57 & 60 are 19mm, but I'm not aware of any that were 18mm.
As you can tell I am not familiar with these type of bracelets. I am ok with 19 mm as I can always file down. Can you provide me a link where I can find something that would work?
I just looked again at the bracelet, and didn't realize that straight ends have been soldered on. These are, in effect, the endpieces. Usually straight ends are designed for cases that are straight, not curved, between the lugs, like the original bubbleback design, so the 17mm ends would fit these bubblebacks. If you need straight ends, you will probably have to look for an aftermarket bracelet I think, that would be your easiest bet. Rolex ones in larger sizes are probably much rarer than the one you have. If you have a later, rounder case, you would need another bracelet altogether I think, a 7205 would be your best bet. Like this one I just found on the web: