[69 Mach I]

Stud mounted rockers screw into the head whereas pedestal mounts are pressed in. The stud mount rockers allow for a stiffer valve springs that you would want if you have an application where your spring open pressures exceed 280# (e.g., a bigger cam or a roller cam). This would cause a pressed-in stud to work lose, which is a bad thing. You want a stud that screws in. You can get 3/8 or 7/16 inch studs. Get the 7/16 studs as they are stronger. The price of the roller rockers will be the same.