will gear whine (decel) or (pinion) bearing noise still be there in neutral?

 

In netrual the input shaft and cluster gear and the idler gears on the output shaft for each speed (excepth 4th) will be spinning. They are not exactly silent, but I would not characterize the noise as a whine.

 

well, i definitely have some whine on decel (more of a flutter) that goes away on tip-in. Also goes away if I shift to neutral. I also have a hum/moan type sound above 25 mph, which is independent of throttle position or gear/neutral. I'm fairly confident the decel whine is the gears, i was mainly wondering if the hum could also be differential related.

 

Usually pinion noise will be prevalent during acceleration or decel, while the mesh is under load. probably loader as load increases. It could be cyclic and / or speed dependent as well.