Gear Box Question

[Michael J. Fodor]

Lately I have noticed " more whine " than " normal" in the drive train. All fluids have been drained and refilled with correct lube in the drive train.
For the lack of a better explanation !
Not only has the drive train " whine " increased, but you can feel and hear what maybe a bearing problem, at first I thought it might be a bearing problem related to secondary transmission, and yes u joints are lube and tight.The noise and feel becomes more noticable around 40 kph, after some " guess work" the problem is more pronounced in 5th or high gear. How was this determined, I have acclerated the truck up to 40 + kph and noticed less noise and did not " feel" what maybe galling or bad bearing, like you hear and feel in 5th or high gear. My guess would be in side load on the bearings would be greater in 5th gear and more noticable. What do you think..... thanks mike goshen, Indiana