GM used to have a wear indicator built into the ball joint, I don’t know if they still do or not. But there is another way to check all the suspension components that rally works. With the wheels on the ground, have someone turn the steering wheel back and forth rapidly through an arc of about +/- 1/8th turn from centered. Under this stress, a loose component will show right up, including ball joints.
With this vehicle, I’d suspect a worn idler arm, its commonly overlooked.