"Whine" around 60 mph?

It might be that your carrier bearing's are going out, or a universal joint is worn and throwing the drive line out a bit. If you find one worn item, I would just go ahead and replace both carrier bearings(if their are two) along with the universal joints. When ones gone south, the others soon follow. Check the rear carrier bearing first. Get under and give them all a good shake and see what you can tell. Also check that the engine mounts and transmission mounts are sound.

Does it do it when coasting and not when accelerating? Or does it do it all the time regardless? Cruise control on or off? Could be lots of things. When is the last time you had the gear oil checked in the rear end???...Dennis