While they do rotate under normal circumstances (they're a ball-and-socket after all) I would have to say that anytime you can easily rotate the rods by hand, they're wearing, if not completely worn out already.
When they're new or still in good shape, you would have a very hard time rotating the assembly by hand.
But the proof of the pudding is to perform "the test" where you have a helper turn the steering wheel back and forth enough to make the tires move a little, while you carefully inspect all rods, links, ends, bushings and bearings. Even things like watching the steering box itself can sometimes let you see if you've got a cracked frame or not.
Still not a common thing on Broncos, but happens often enough to be aware of it.
Even with your new trackbar bushings you can still see the trackbar move side-to-side if your bolts are worn, or the holes in the bracket are wobbled out, or your lower stud has broken loose from the mount. Since it's just a big bolt tack-welded in place, if that weld cracks you will get some movement that can lead to wandering down the road.
All of it adds up. Heck, if you go out back while the helper is sawing the wheel back and forth, you might even find a loose u-bolt or bracket. The tires will push things that much.
Of course, the tires have to be fully on the ground for this test to work. Any weight taken off the system will lessen the effect and hide some worn parts.
Good luck. Well worth the five minutes of your time.
I recommend doing it any time your Bronco seems a little "loose" or twitchy. As often as needed.
Paul
