Help diagnose noise...rear diff?

I just came back from a 5k trip from MD to CO and back and developed a noise under acceleration about half way through the trip.

At first I thought it was something loose with the exhaust. I had swapped out the stock, then wife vetoed the new exhaust (loud as f*ck when towing, I agree) so I thought maybe I needed to tighten down exhaust bolts or I missed a hangar....that's not it.

The sounds starts to show up at about 30-35 mph and gets louder as I speed up -- but ONLY when I'm accelerating. If I take my foot off the gas and just coast it sounds normal.

I've got about 10k miles on a Nitro 5.29 set of gears and starting to think that something might be wrong...was under the truck looking for something loose and the rear diff was still warm to the touch about 30 mins after parking. It's a 2020 sport with only 25k miles but has seen a bunch of towing...

Thanks for any ideas!

 

Just a starting point. Open the fill on the rear diff while sitting level. See if any oil runs out, or if you can feel any with the pinky finger test. If not, start adding. Might be time to just change it anyways if you have towed a lot.

 

Yeah change the rear diff fluid, and see if you notice any shavings or chunks.

 

What's the noise sound like? Whine? Hiss? Clank? Rattle? Light throttle or heavy?

 

Ok update -- changed out all the fluid in the diffs and the transfer case. Oil was dirty but nothing that looked too bad. Noise is the same...it sounds like light tinny rattle. Happens when I'm light on the gas, even just tapping it.

 

Exhaust heat shield somewhere?

 

I've been under there looking for something loose and don't see anything...at this point I might just start taking things off!