P/N 7170-00031 60B11 – 1-1/4in Bore For reducer shaft @30 fpm (head speed) P/N 7170-00020 60B20 – 1-1/2in Bore For Drive Shaft From Reducer P/N 7170-00014 60B22 – 1-1/2in Bore For Drive & Idler Shaft (Head Transmission)