Mike,
That looks like the factory shaft seal. Is it?
I'm trying to install the 915 "dam seal" mod discussed in other posts.
For example.
http://forums.pelicanparts.com/showthread.php?threadid=196173
It is essentionaly another seal that gets installed behind the factory shaft seal to stop leaking fluid from making its way to the clutch. A hole is then drilled between the two seals so the fluid drains harmlessly out of the bottom of the bell housing.
There are quite a few people who have done this mod. I'm hoping someone has a part number for a seal that works with the later 915 removable guide tube.