Rocker Shafts - Set - M8Custom tooling was created to provide a countersink relief for the bolt nut head versus machining away the entire end of the shaft per the factory design Recommended for all M Eight engines and especially for engines running higher lift camshafts and heavier valve spring pressures Over double the strength of factory rocker shafts Gas nitrated and final surface treated Precision ground from 4140HT steel Designed with strength in mind Made in the USA