The bearing on the driveshaft in the bottom of the chaincase (bearing number 6205) has one seal on the bearing. The seal faces the inside of the chaincase. The purpose of this seal is to keep large metal debris from damaging the bearing. The seal allows enough chaincase oil to pass by it to provide lubrication of the bearing. I know there is a lot of debate about this seal, I choose to use it as intended, to protect the bearing. There is a seal on the driveshaft on the side of the chaincase which faces the track. Between the outer seal and the 6205 bearing, there is a cavity which should be filled with a good, water resistant grease. I have replaced the lower chaincase bearings on my sleds with stainless steel versions of the 6205 bearing. The stainless steel bearings are expensive, $35 each, but they will not corrode due to water which accumulates in teh chaincase under normal use. I always remove the outer seal from the lower chaincase bearing to allow the grease to have full access to the ball bearings. I have never had a lower chaincase bearing fail, even after 13,000 miles on some bearings. It is very important to remove the cover from the chaincase to drain and FLUSH out the accumulated metal debris. Removing the plug to drain the chaincase will not allow the metal sludge to drain out.