I have a 2003 Pathfinder SE with 104,000 Kms (64,000 miles) on it and
I'm experiencing some strange clutch noise.

When the vehicle is cold, if you depress the clutch there is a strange
noise that could be described as: whirring, vibration, groaning.  Not
grinding.  Not squealing.

The noise goes away after about 10 minutes of city driving.  Also, it
seems to be more prevalent the day after the vehicle has been driven a
long distance on the highway Ex: 200-400Km (120-240 Miles).

The noise can be heard with clutch depressed while the transmission is
in neutral or shifted into any gear, except 4th.  In 4th gear position,
the noise stops, but starts again if shift placed into another
position, like second.  Clutch depressed the whole time (were not
moving).

I had it to the dealer for a listen and they seem to think it is a
transmission, not clutch, problem.  Their reasoning being that if it
was a clutch problem, the gear selection position would not matter.

Granted, I'm no mechanic but I'm not sure about their diagnosis.
Everything I've researched points to either a release/throwout bearing
or pilot bushing problem.

I don't want to go through tranny replacement if that's not the problem.

Any thoughts?