What is the difference between these two items? I've got a small knob at bottom of my dash that says Park Pilot, but the manual doesn't explain what this knob/dial does. The truck does "beep" a lot but there is no indicator to show me how close I am to an item. Maybe I have to get used to the beeping to be able to judge how close I am. Also, maybe the dial/knob adjusts the sensitivity or the volume. Can anyone help me? This is a 2007 DC SR5.