The most reasonably priced component used on the C86z 1979 (z) Cub Malaysia E-4 Cam Chain - Tensioner is the Nut,hex.,8mm.
The twenty-one C86z 1979 (z) Cub Malaysia E-4 Cam Chain - Tensioner component parts are all listed in this schematic.
On this parts fiche the Bolt,knock,5mm is the most specified component.