2001 Olds Bravada noise from rear axle when driving

Check your brake pads and rotors for extreme wear.

Depends on the noise. Tapping or knocking is rod bearings, engine side. Whining is the transmission side. Torque converter, pump, and parts further inside the transmission.

Check bearings.

make sure the axle joint didn't fail then on the pass side of the car behind the axle there is a cover that houses the differential open that and check the gears in there

This noise is more likely caused by the iiner constant velocity joint. When turning the axle makes a franction of an angle in which no perpendicular to the ground. You'll gonna need to have it check as there is a possiblity that the wheel drum or axle assembly might come off when driving in high speed to avoid accident.

the fan clutch is stuck not allowing the fan to free wheel like its designed at an idle Replace the fan clutch

Bad wheel bearing assembly's are a common issue. Any difference when turning hard left or right while driving?

might be a faulty power window motors & switch (s)

Try making tight turns to the right and then to the left. see if the grinding noise comes and goes. It could be your C/V joint and they need to be replaced. The noise will only come when your making the tight turns, you don't have to go fast. Walking speed will do and you can hear it with the window open or someone walking beside the Bravada. Good luck and keep me posted. Be glad to help.

your problem is more than likely one of a few problems
there are two hoses on your transfer case one sucks in one blows out if one gets cloged it will go out completly so have it checked its starting.
or check the oil in the transfer case