This is the 8-32 NC tap and #29 drill you will need if should should decide to grind off any of your old linkage arms or center carb. throttle arm and keep the existing throttleshafts. You will need to drill and tap the end of your existing throttlleshaft for the new screw to attach your new linkage. The #29 drill bit I include has a split point on the end this will reduce the thrust and eliminate the drill from walking at the drill point. I have found that it is not always that easy to find these at the local hardware store. Save yourself several trips!