To find the correct spark plug, you must consult your owner's manual. The manual will specify the correct type, heat range, and gap for your specific year and model. The information will be in the maintenance section.
Failing that, you can:
* Check a reputable online parts store: Websites like AutoZone, Advance Auto Parts, or RockAuto will allow you to enter your vehicle's year, make, and model to find the correct spark plugs.
* Visit a local auto parts store: A knowledgeable parts professional can assist you based on your VIN.
Providing the year of your Lincoln Town Car will allow me to give you a more specific answer, but relying on the owner's manual or a parts professional is the most reliable method.