Just got an 01' and it has a problem wen braken at low speeds. It will a droneing frome the drake pad area and the brake pedel gets hard as a rock. It only dose this when the cluch is pushed in and going like 5mph .
And 4x4 dosnt work. It shifts into low range so I dontthink its the tranfercase.

 

Your brake pads are prolly shot, famous for only wearing on one side as calipers stick,

 

my brake pads look newer...

 

hard to believe but i had the same issue with my truck on the 4x4 issue. there is a vacuum line that can come loose from the pump to the vacuum collection area on the fire wall. check and see if this is the problem. I know i thought what the crap dose vacuum have to do with it but it fixed the problem!!!