Remember that bridge in washington state that ripped apart in the wind, that is DW on a vehicle. If you think you have DW you don't have it. You will know when you have death wobble as you will want to stop to save your life.
It is the side to side motion of the tires that you feel, but the axel is most likely going side to side which causes the tires to move side to side. Several things cause DW. Steering, unbalanced or bad tires, bad bushings in your shackles, loose leaf spring bolts, worn out bearings in the front axel, worn out ball joints/king pins. Steering stabilizers only hide the problem. If your vehicle has ran fine and you just started getting DW I would strongly recommend you get the whole front end and tires checked over before buying a Steering Stabilizer or trac bar as something is getting ready to fail. As mentioned there are thousands of these chasis that never experienced DW, those that have it most likely have something going bad.