rear dif making constant humming noise

What is your question?

the noise stays constant relative to vehicle speed whether the vehicle is in gear or not. meaning the noise speeds up as you speed up. it stays constant if vehicle speed is constant and slows when the vehicle slows. there is no vibration or clunking noise. I changed the oil in the differential a week ago. no leaks.

How long has your 2008 Pontiac Torrent had this problem?

several weeks