1061898
as the sound is proportional to road speed and diminishes when there is no load on the drive train, it is possible that your ring and pinion is wearing, or has water in the gear oil.
have you been in water over the hubs lately?
there are a few things that may whine in the drive train, but you'll have to rule each out.
wouldn't it be funny if it was a big oak leaf stuck under your chassis rubbing on something.
stranger things have happened.
[addsig]