Chevrolet Repair: 1991 Chevrolet S10 4.3L 4x4 5-Speed Transmission Problem, shaft bearings, output shaft

Question
This is a follow up on my previous question. You had asked if the pitch of the noise the transmission makes is different in each gear. No, the noise is the same pitch in each gear and only changes with engine RPM. When the clutch is pressed or when I am between gears during shifting there is no noise. 4th gear is the only gear that is noise free.
Thanks

Answer
Then I would say it is main shaft bearings in the transmission.
In fourth gear is the only time the input shaft, and the output shaft turns the exact same speed, since it is direct drive.
Each other gear is either overdrive, or a geared down underdrive, so-to-speak.


Van