Check out any of the twenty-one Alternator components enlisted.
In this schematic the "Bolt,socket 8x18" is used most often.
Parts such as the Alternator: Bolt,special,8mm, Flywheel, Bolt,flange,6x28, Stator Comp.(nd) are included in the Trx125 Fourtrax 125 1987 (h) Usa Alternator parts fiche.