I am unsure of the name of the shaft but its the shaft that the oil seal, water pump mechanical and impellar sit on. I have had major issues with a leak since i bought it and when i went to replace the water pump seal i found that the shaft was already broke between the water pump mechanical and the oil seal. So anyone know the name of the part I need to track down to fix this and how difficult is this to replace yourself? I assume it will involve removing the engine? I have a 2002 polaris sportsman 400. Anyone with any advice I would appreciate. I live far in the woods so traveling for repairs would be costly and time consuming. Thanks for the help.