The benefit of using on line parts illustrations and part numbers is that you see when parts have been upgraded or no longer available and cost.
In the next year or two there could be other versions of the BX2680 made and serial number breaks apply in selecting parts. These important facts do not show up in paper documents.
The same Kubota model may be sold in other countries and subtle differences not reflected in paper documents which tend to be used for many countries who speak English. A case in point would be brake lights. WSM's often show brake lights but in North America they are not required and are deleted during manufacture.
tthorkil pointed you to Kubota.usa.
I tend to use Messicks and sign in as a guest.
Messicks
Coleman Equipment is another prominent parts supplier.
Dave