55156923AE is the part number for the 2005-07 Liberty Renegade fog lamp. They list for $95.75 here at the dealership.
As far as lights and their uses and DOT markings, most states are no overly strict on fog lamps but technically they have to be 55 Watt or less and have a fog pattern. Most for lamps will be marked either "Fog" or "DR or Driving" to designate the pattern that is cut into the lens. Driving lamps are more like pencil beams and throw a more narrow, long distance beam. Fog lamps throw a short distance, but very wide beam. The lamps on my '06 Renegade are very well done and have a very sharp beam that cuts off suddenly, but really illuminates the area in front and to the sides well. In most states you can get by with a 4 lamp system at one time. Meaning two low beam headlamps and two fog lamps. In Virginia you are also allowed to run driving lamps as long as you only have a two headlamp system or the low beams do not stay on with the high beams. So either way you only have a maximum of 4 lamps on at one time. If you had a car or truck that used 4 headlamps and the low beams stay on when on high beam then you could not run driving lamps. Some states have weird rules regarding how lamps are switched. some require a toggle switch, some require them to come on and go off on relays with the factory high and low beams, and others require both. Check your local laws, blah blah blah...
