Rear brake?

[Ch3vY]

I have a 01 Silverado 2500HD long bed and it seems for the past while a bad smell has progressively gotten worse, it is the strongest in the rear driver wheel well. The burning smell I've been told is from my park brake which I use quite often, is this commen for them to get stuck and still drive? It stinks the most after I drive it for a bit. I've also been told it could be the rear diff but I just changed the fluid, they are also disc brakes in the back.

[txab]

Pull the wheel off and completely inspect the braking system........