just a quick post to see if anyone has an idea about what's going on. 144k miles 5spd I bought it 2 weeks ago and it was making a whining noise when the clutch was not pushed in. I have no idea how long it had been going on. now the the whining noise is seldom, but instead there is a metallic hollow kind of sound in any gear. it's not that loud but it is noticeable. it does not go away if the clutch is pushed in. it doesn't get louder if I rev the engine either. it's just constant. I think they're related and a part has moved into its next evolution of failing.
Noise when the clutch is pushed in should suspect the throwout-bearing ( throwout-bearing only spins when the clutch is pushed.)
Noise that happens ALL THE TIME even in neutral or clutch pushed does not suggest anything in the clutch area or the xmission.... however, you say it it heard "in gear" so I assume you are saying "while moving".
In that case, I would suggest you make sure there is lubricant in the xmission and rear differential.
I will check the gear oil. dumb question but I've never owned an awd car. how do I check the diff fluid levels? and do I use the same oil for the diffs as the tranny?