When I did mine purchased a street hemi(567)half inch pick up.Installs when tightened and lined up perfect.My milodon 30930 half inch pickup starts to tighten and then spins to bottom of threads,if I ever do this mod to another block will tap in increments to avoid this in future.I am very good at learning things the hard way but like to pass on so others don`t have too,unless they like it.....