with clutch pedal up (engaged clutch) and neutral (no gear) with engine running, the countershaft makes this noise as its thrust is incorrectly set or the bearings are a bit shot.
This sound is also caused by the clutch friction plate hub springs being loose.
The thrust bearing when bad only makes noise when the clutch is pressed in (disengaged) as it presses on the pressure plate when you press the pedal to unclamp the clutch friction plate.
The proper remedy for this noise in this car is to check the parts to identify the source of the noise.