Gooster

Hello all! The past few days I have been noticing a high pitched whine from under the car, I lifted it up today at work and we narrowed it down to the back half of the transmission just in front of the drive shaft, or atleast we think that is where the noise is comming from, any ideas on what it could be before we go tearing into it?

edit: noise only occurs while driving/in gear and moving

edit #2: I am familar with clutch buzz and have experienced it, how ever I am fairly certain this has nothing to do with the clutch, it makes the noise when accell, cruising, or decel...pretty much anytime the wheels are moving it makes the noise, even with the engine turned off and moving the rear wheels by hand you can hear it very slightly with an automotive stethoscope. this noise sounds like a wheel bearing starting to go out, only it is from the rear of the transmission.

Is this a common problem, or is it more or less unheard of?

By the way the car is mostly stock, no work on the rearend or anything, factory clutch at 91k, no slipping and no problems in any gears, fluid has been changed regulary, and was done about 5000 miles ago, checked fluid level today, still full, still looks brand new. thanks for any help!