4130 stud and nut kit replaces the stock hardware used to secure the rocker shafts Compared to a stock ôboltö, these JIMS manufactured studs allow the technician the assembly finesse required when torqueing the rocker arm shafts on the cylinder head during engine assembly These shafts not only improve the stock head configuration; they are a must in a performance application with increased spring pressure. SHAFT ROCKER ARM HW KT M8