I have a slight rear end whine from 60-65mph, it is there when I am appling the gas but goes away when I let off. It's only really noticeable in the 60-65 area. Any ideas, my fron pinion seal was leaking ? Bearing out ?

 

Mine has the same problem and was like this when new. Went to two dealers and both said they couldn't hear any whine. Bunch of deaf ********.

 

If this just started happening and you've had your gears for a while it may be a sign of your gears going out of alignment. I would check for leaks at the pinion seal and cover seal.

 

I had a pinion seal leak and repaired it, got me thinking though.
I am pretty sure I have a pinion bearing that went bad. The gear lube is toast from heat.