On the 7/8" shoes, the original Super 2100 parts list shows only the 7/8" shoes. The Rev 1 print (as Bill just posted) shows it can come with either the 3/4" or 7/8". There's a service bulletin from April '73 that states that as of serial number 30871001, all the Super 2100s would be fitted with the 3/4" shoes, essentially doing away with the 7/8". There's no explanation why they were changing. Showed the "updated" part numbers for the crank, drum, spider, shoes, spring and clutch cover. Wonder if it was to save money, or if there was some failure or safety issue with the 7/8" clutch :confused2:.
Dan