The most reasonably priced component used on the Dt50rsm 2005 2c37 Holland 1d2c2-300e4 Cylinder Head is the Arandela Plana.
Some items from this specific schematic: Plug, Spark (br9es), Gasket, Head Cover 2 (nas), Arandela Plana, Tuerca Corona.
On this parts fiche the Tuerca Corona is the most specified component.
