A sample from the products for the Oil Pump include: Cover,oil Pump, Pump Assy Oil, Valve Assy., Relief, Bolt Flang 6x12.
The most reasonably priced component used on the Trx350d Fourtrax 1987 (h) Italy Sul Oil Pump is the Screw Cross 5x22.
On this parts fiche the Screw Cross 5x22 is the most specified component.