I hear some rattles when going over bumps and think it might be my sway bar links based on some posts I have read. I see they are really just a bar with ball joints at both ends. What causes them to go bad, and how can I tell? Is it just that the ball joints go bad on the bar? I've read from some that there are some sort of rubber bushings--I didn't really see any. What goes bad with these things?

thanks,
db