[lincpimp]

I am going to guess, that unless he made his own slipper shaft, it is a revo input shaft, al of the revo slipper components, a 20t pinion that is affixed to the shaft somehow.

My revo uses the input shaft, I ground a flat area on the shaft, where I wanted the pinion to stay. I then used an al tube to keep the shaft centered between the bearings. It just fits between the pinion and the rear bearing.