Upgrade to stronger mod 1.5 spur & pinion gears! — Standard 5 mm motor shaft with D-shaped flat. — Traxxas cush drive. — 12T/35T combo for X-Maxx. — Fits E-Revo 2.0 as high- speed gearing. — Fits XO-1 to add strength. — Thanks for looking! Check out my other listings.