Burning smell near rear-end?

Did you put your hand near the drum to see if it was warmer than normal. I just had the distributing valve (or whatever you call it) go bad. If I was lightly on the brake it would not completely release the brakes when you took your foot off the pedal. If i really pressed down hard to increase the air pressure it would vent all the air like normal and release them completely.

 

Check the hub oil level, leaking wheel seal? Something is rubbing on something.

 

If you have a burning smell, then something's getting hot somewhere.

If it's worth $300 to you, then pick up a thermal imaging camera. You'll find the hot spots quickly with that.

 

Usually if a wheel bearing is going bad, an oil leak is a symptom, so if @Steel Tiger's symptom is there, then check the wheel bearing while you have it apart. The last company I worked for only used Internationals and the shop was always doing wheel seals

 

Could be an axle bearing as well. I'd stop by a shop and finger it out, before you maybe drive around with no oil in the rear end and wind up with something real expensive.
No visible oil leaks means your in luck and its not too far gone.

 

I use a infrared heat gun works well for heat, but have to move slow to find hot spots on a circle. Only run you about 85 at your local parts store.