This spur uses an aggressive Mod1 pitch and is a 43T gear.  This is designed to fit on the Ground Pounder transmission output shaft and allows the use of the stock slipper clutch system. 

Pinion gear not included.  You will need to purchase a suitable Mod1 pinion gear to run with this spur gear.  Examples of stock and aftermarket gearing provided below.   In general, a higher tooth pinion gear will provide more speed while a lower tooth pinion will provide more torque.

Stock Gearing:  81T Spur / 23T Pinion = 3.52    Aftermarket Gearing:  43T Spur / 12T Pinion (not included) = 3.58