I thnk it's 1/2" 13-20 (fine ) That was for main shifter, not sure if they are the same. I work at a hardware store, so I took a handful of coupling nuts out and tried till I got one to fit. I ghetto <img src="/forums/images/graemlins/mrt.gif" alt="" /> extended the shifter cause of my body lift used a 7"piece of all thread and coupling nut(wrapped it with elec tape function before form I always say <img src="/forums/images/graemlins/smile.gif" alt="" /> It is much nicer with shifter same height as wiper controlls. <img src="/forums/images/graemlins/smile.gif" alt="" />