1/3 HP & 1/2 HP Motors feature a 1/2" Shaft
3/4 HP, 1 HP & 1 1/2 HP Motors feature a 5/8" Shaft
The 3/4 HP now has a 5/8" Shaft. If you are replacing an older 3/4 HP motor please make sure you replace your pinion gear to a 5/8". #FLX-4276