That's very interesting is 'that' See what others say & thanks for posting.

Which ever one you buy or use, be sure to line the 2 little dots up on the back side when putting this assembly back together. 

Yamaha was very diligent at marking updated parts with a unique suffix such as "-10".  It would be unusual for them to make such a dramatic change to a part and not identify it. 

Ebay sellers are also very good at posting parts next to Yamaha packaging...  packaging they often don't send with the part...  so there is a chance that several sellers are listing the part with the extra teeth incorrectly?   (Note the ebay auction you linked to showed the two different parts and one package)

There is a similar part with a 363- prefix that was used on the SC500 that does have the extra teeth... and seems to have been superseded.  It might be possible some sellers are misidentifying the part and the one with more ratchet teeth is actually a 363-15671?

i.ebayimg.com/images/g/IoMAAOSwETJaDHXS/s-l500.jpg

Ebay 363-15671 SC500

The key is checking to see if the ratchet teeth engage properly with the mating gear.

The dot on the kick start shaft is extremely hard to see or may be gone. As for the line up, i think it changes the spring tension after its all assembled and back in place if not correctly lined up.