Check out any of the eighteen Oil Pump components enlisted.
The Gsf1200 1997 (v) (e02 E04 E22 E25 E34) / P37 Oil Pump consists of eighteen pieces with the Pump Assy,oil being the most expensive.
With a quantity of four pieces, the O Ring(d:3.7,id:21.7) is the most used part in the OIL PUMP diagram.