Drive Shadt and Impeller??

Today I emptied my gear case of the old oil and put in new fresh gear case oil. Afterwards I decided I should check my impeller to make sure it's still intact, and it was. As I checked it I noticed the drive shaft looked very dirty and so I wiped it clean (it looked like it had old grease or oil on it). My question is does it (the drive shaft) need to be greased? Also if the impeller is installed upside down the water pump will not pump correctly and therefore not cool the engine?

I'd say the oil/grease on the shaft is normal. some unburnt fuel will cake up on it. On the top of it where the splines are and goes into the power head,I usually put a small amount of grease on it. For the impeller ,I don't think it matters. The only thing I make sure is that the vanes are twisted the right way when it goes in to the water pump housing.

I don't know if it needs greased but I did mine about 4 days ago. And the water pump wouldn't shoot water out the peehole if backwards.

Most impellers if not all can not be put in backwards.

I put a new one in every year.Cheep insurance.