I have done a search of the board, but was not able to find my answer. My 90 has a bearing noise coming from the driveshaft behind the front sprocket. Does anyone know if I can change the  bearing with out taking the engine completly apart?

The bad news is the engine will have to be removed from the frame and the cases split to get at that tranny bearing.  The good news is the engine won't require a complete tear down; the top end remains untouched.  It's a job but not a lot of thinking required as most of the technical stuff is bypassed.  This would also be the time to easily change all the seals.  Just be sure the bearing is the source of the noise and not the chain. 

You have to split the cases to access the bearings. They have a retaining ring.

the long part of the job is  engine R&R
the pain in the butt part is cleaning the mating surfaces of the cases
the easy part is the bearing R&R

I was afraid of that. Thanks for the info guys. Guess I will start rounding up the parts to fix it.