I doubt that you would hear a rattle from the ball joints? Might be the shock mounting bolts not tight enough. To do a preliminary check on the joints, jack up the front wheel to be checked and support the weight as far out toward the wheel as you can get the jack stand, just make sure the upper control arm is not touching the rubber bumper, have someone observe the lower ball joint, put a bar under the tire and pry upward and release, if there is any movement then the joint has some wear, on a 99 the max. allowed is . 030". You can push in and pull out on the top of the wheel and see if there is any play in top joint. There is a more specific and precicion procedure for checking the wear and it requires the use of a dial test indicator. bg