I had trouble finding mine too. Their is a little rounded off piece of metal that protudes off the brake caliper. What I did was put the car up on ramps ur something, crank the wheel all the way over, and look for metal-to-metal contact. I wish I had a digital camera...would be a lot easier to explain. Its rubbing surface is a little metal square welded to the rear section of the lower control arm.
"Responding to a question by saying do a search, look in a auto parts catalog, or call a mechanic isn't being helpful"
2003 Grand marquis all stock