My experience is the ends (ball joint) wears and could eventually break. You can check them simply by grabbing it and checking for any up/down motion. Also, while it should move back and forth, it should offer some resistance to you doing so.
On another note, you can maintain them by greasing them. Even if they do not have grease fittings, you can use a needle made to go on the end of a grease gun and slipping it in between the post and boot. If/when work is done around the front end, it is not uncommon for you or a mechanic to inadvertently push against the boot of the joint squeezing the grease out.
If the end breaks off, you cannot drive the truck. Actually, the truck may just drive you.