Auto body repair & detailing: Fender Bolts, fender body, jeep wrangler

Question
I have a 99 Jeep Wrangler and want to add some mud flaps as well as some "body armor".  There are several bolts that attach all the factory fenders to the Jeep body and I need to remove them in order to accomplish my goal.  However, when I attempted to take them off, all they did was loosen and then just kind of spun in place.  Never actually coming out of their grooves at all.  Every single one of these are exactly the same which makes me think that there is something special to removing them that I'm not aware of.  Obviously I'm no expert, please help.

Answer
The Wranglers will have nuts, usually welded, inside the fire wall. Look under your dash, pull back the matting, you should see them all the way to the top. You should also find them under the car, at the front of the body at the fender body seem. If the welds broke loose, use a pair of vise grips to hold the nut.