clutch hub bearing

Some where is a thread on the clutch hub bearing. i can't find it so here are my questions.
1,The original is open and i guess splash lubricated from the primary oil?
Should this be changed to a bearing with steel or rubber seals?

2 My manual cautions me about being careful of a seal on the rear primary case as it goes over the gearbox shaft. My 850 II doesnot have a seal except for the movable sheet metal part that keeps muck out of the primary case. Am i missing a rubber or felt seal from the rear primary case that goes around the gearbox shaft?

Thats for your input
David

I use a sealed bearing whether using a belt drive (dry) or chain (wet). The oil in the chaincase is mainly for chain lubrication and most people these days use a lesser quantity and a thinner oil than specified to try to prevent clutch slipping. The double sided metal sliding plate you mention has a felt washer sandwiched between the two plates where it goes over the shaft. With age they get black and can look like a solid piece of metal.