The twenty-one Xl500s 1979 (z) Belgium E-10 Crankcase component parts are all listed in this schematic.
Parts such as the E-10 Crankcase: Bolt,flg.,10x166, Pipe,oil Pass, Bolt,hex 6x12, Plate,breather are included in the Xl500s 1979 (z) Belgium E-10 Crankcase parts fiche.
The Bolt,hex 6x12 is the cheapest item from this partsfiche.