I drilled my own holes on my old TC3 arms & used 12th scale 4-40 setsrews from the dampner tube for droop screws. I ran these 2 years before they came out with them on the cars. I never broke an arm because of the holes in them. With the size of foam tires changing all the time you have to use droop screws because of the amount of times you need to adjust them. R.W.