I just noticed I have a low hum when I climb a hill or steep bridge. The hum comes and goes as I go up the bridge. I would bet the humming is coming from the transmission area, maybe the tourque converter. I took the truck into the dealer for another issue but explained the symptoms and he suggested it could be the rear differential.

Has anyone had these symptoms and what was the fix?

 

 

I had a hum from my differential a couple of weeks ago. The forward seal had leaked, and a pinion gear got damaged. All this at only 61K miles. Wish I still had my bulletproof 95. Check your rear fluid right away. Look for any signs of a leak around it.
T