Yup, you should start tearing into that tranny cause that's the only thing between your clutches and your propeller shafts front and rear. Sounds like it could be a bevel gear if your not moving at all. Or a shaft in the tranny. What ever it is i'm sure it'll be expensive so if you are mechanically inclined grab up a repair manual and get to it.
P.S The manual will help out alot cause there are ways "to" and "not to" tear these things apart.
P.S The manual will help out alot cause there are ways "to" and "not to" tear these things apart.