I had the same problem when I replaced all the plastic gears in my 445. I just bought both sets and then matched to the ones I needed when I disassembled my engine. Cost of the unneeded parts was not that much and was a lot easier than going to the dealer with the old parts in hand, ordering and then waiting for the parts to come in.

 

the only place Kawasaki put it is on this tag, if it's gone or unreadable, you're gonna have to do some guessing and matching. If you're tag's still readable photo it or write don't all numbers on the tag!

when I was working at Deere back in the 90's and 2000's the service department could run the serial number through Deere's system and get that info, not sure if they can still or would be willing to take the time.