Jack up one side of the truck so the tire is maybe 1" off the ground. Slip a large prybar under the tire and attemp to lift/push tire in while looking at the ball joints. Repeat for other side. Check the tie rod ends and track bar end with a pair of groove joint pliers by trying to squeeze the joint together. If you see any movement, the joint is worn. If you need to replace the ball joints also check the front axle U-joints if it's a 4x4 as your already there.