I drive a stock 96 2WD with the 4.0 engine, recently it has been making a noise at slow speeds, i want to say speeds less than twenty-ish or so, so far i have had my tires rotated and balanced but that hasn't really done anything. As far as i can tell nothing is leaking. The noise kind of sounds more like a grinding than a knocking and sounds to me to be coming from the front and not the back, though i may be wrong.