Track arms (the tuning forks). Replace both sides. You can't test them while they're on the car. The ball joint where it attaches to the body has a plastic bushing inside it that wears out and causes metal to metal noise. Unfortunately it's not a replaceable item, you have to replace the entire track arm.
https://www.pelicanparts.com/More_Info/98633104307M80.htm?pn=986-331-043-07-M80&bt=Y&fs=0&SVSVSI=1049