Bob,
Hermy's
TriumpheStore shows a chain and sprocket kit for the America (A9618015)and the SM (A9618019). The picture shows an 18t gear. I know that's not proof positive, but you might send them an email and ask if they have a p/n for the kit you're looking for. I have a brand new 18t Triumph sprocket I bought off of ebay, but it doesn't have a p/n on it. Just 18T and 525.....
