On this parts fiche the Washer, Cover is the most specified component.
Parts such as the Front Cover: Cover,fr. *nh138*, Washer,plain,8mm, Hook,fr.cover, Bolt Special 6mm. are included in the C90st Cub 1999 (x) Mexico / Csw Ss Front Cover parts fiche.
The Washer,plain,8mm is the lowest priced item on this Front Cover schematic.