verktyg has the posts to end all posts on the subject. From this thread:
Pro Miyata shifter bosses
edit: Looks like quoting from a different thread didn't bring the pictures. Just go to the thread linked, it has everything you need I think.
Originally Posted by
verktyg
Rokudenashi-ko! Japanese vulgar word for Bastard! (Bātard in French, Bastardo in Italian, Spanish and Portuguese) as in questioning the legitimacy of one's heritage!
Attachment 451014 Attachment 451015
Shimano used 3 distinct types of lever bosses:
Attachment 451004
These "crescent moon" boss covers were for use with de facto standard Campagnolo style bosses or Shimano "A" style bosses:
Attachment 451005
The boss covers were an integral part of Shimano's shift lever system and you have to have the correct ones for your application or else it's a lot of work to modify the bosses.
Shimano made some conversion kits to use A style levers and Campy style bosses - opposite of what you need.
Attachment 451008 Attachment 451010 Attachment 451011 Attachment 451012
I've seen a few of these pop up on eBay.
I think that they also made some uber rare conversion kits to mount Campy style square boss levers on Type A bosses too.
Some of the boxed index lever sets came with both styles of "crescent moon" covers plus 4.5mm and 5mm screws.
Type A clamp on levers:
Attachment 451013
Check around they junk boxes at some LBSs, that's where I found the crescent moons that I was looking for.
Attachment 451018
verktyg
Chas.