recently (or maybe i just haven't noticed until now), i can hear this very slight higher-pitched humming coming from the rear. it is not loud and sometimes you actually have to concentrate to hear it. the sound is only audible from 51-58 mph give or take 1. it seems to go away once you're over 60 and under 50 mph.

accellerating and braking have no effect on the sound. the sound is not affected by turning the steering wheel in either direction. i had a to replace my front hub assembly before, and this sound is similar, but nowhere near as loud. and this is higher pitched. you can't hear it when the radio is turned on, even when the volume is quite low.

the car still rides smooth and tracks like it always has.

i'm hoping it's just road noise and maybe the tires just get a little louder at that speed. i'm gonna go check the tire pressure now, just in case that's the issue.

is it possible that the differential fluid is low or needs to be changed? i'm having it checked on thursday anyway so...

any ideas?