Halogen Headlights Set Driver Left and Passenger Right Black Housing w/o sockets Pair Fits 03-04 Mercury Grand Marquis 03-04 Mercury Marauder

For the most part, no. The stock replacement headlight assemblies are a direct equivalent to what is being taken out of the car. You can reuse your old bulbs and sockets, which should fit right in with no modifications needed. Some of the aftermarket units do use different Halogen bulbs than the stock ones. In those cases, we sell the requisite bulb, and really, with the great deal we have on PERDE light bulbs, you can't go wrong with fresh, new bulbs.

HID stands for "High Intensity Discharge". These bulbs use an electric arc rather than the glowing filament in a Halogen bulb. HID headlamp bulbs do not run on low-voltage DC current like a Halogen Bulb, so they require a ballast, which controls and regulates the flow of current. This ballast will require an ignitor to light the bulb. This is either integrated directly into the bulb or as a separate unit which is occasionally part of the ballast, similar to fluorescent bulbs in your home. In a vehicle, HID bulbs tend to be much more expensive to replace than a Halogen bulb.

Xenon is an inert gas that allows a bulb to produce a brighter light with a longer life than a standard halogen bulb.