thanks for the responses.
i have joined the yahamaenduro site as well.
this one is phenomenal though!
i am going to replace both the shift shaft and crankshaft seals.
the year of my bike is a 1980 dt175cc
so i don't know if it will have the o-ring you speak of, though i will look.
(ps:i really hope this bike runs better now that i've got por15 all over my hands from lining the incredibly rusted gas tank. looks to have done a pretty good job. thousands upon thousands of times better shape than it was prior.)
on the other side of the bike, is there a gasket for the gearbox cover or anything? that looks like it could potentially be leaking as well.
thanks a ton for the replies folks!
(first they ignore you, then they laugh at you, then they fight you, then you win)