The balljoint in the lateral lower control arm is fixed. There's no balljoint in the radius arm/tension strut. That one's balljoint is in the knuckle.

Still, it's extremely cheap to have a bushing pressed in, so if the balljoint in one of the lateral arms develops play, change the whole arm at that point. No point in spending an extra $60 now when a part is fine.

Btw, the radius arm is $160 v. $40 for just the bushing.