[Kawazar]

That is usually the front drive axle or the CV joint as it is also called. It usually makes that noise at low speeds. It won't have any real effect on the operation, you just don't want it break while you are using the 4wd. Autozone has the part for $130 after you return the core. However once it breaks I don't know if they will take it for a core. That would add $62 to the price. Its not a real big job to replace it. Remove the wheel, brake caliper, the spindle and other things just to give you an idea as to what is involved. Probably less than 4 hours for a shop to do it just for a guess. I am no expert either just a DIY guy giving some direction.