Lincoln LS front side marker bulbs use 12961 size while rear side marker bulbs use 3157 size. The replacement chart covers 2000 to 2006 model years with corresponding bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Lincoln LS uses the 12961 bulb for the front side marker position across all model years from 2000-2006.
The 12961 is a Philips part number designating a miniature wedge bulb in the T10 form factor, fitted with a W2.1x9.5d base, rated at 12V and 5W.
The T10 wedge base of the 12961 is a push-in type, meaning it seats without a twist-lock mechanism, which is a common trait of low-wattage marker and courtesy bulbs.
The rear side marker position on the Lincoln LS uses the 3157 bulb across all model years from 2000-2006.
The 3157 is an ANSI-standardized bulb recognized in both the United States and Canada, housed in a T25 wedge form factor and rated at 12V with a dual-filament configuration of 27W and 7W.
The dual-filament nature of the 3157 means it carries two separate circuits within a single bulb, one for a higher-intensity function and one for a lower-intensity function, which is typical of bulbs serving combined stop and marker roles.
The 12961 front marker bulb and the 3157 rear marker bulb are not interchangeable with each other, as they differ in base type, physical size, wattage, and filament count.
The wattage difference between the two bulbs is substantial, with the 3157 rear bulb drawing up to 27W on its primary filament compared to the 5W draw of the 12961 front bulb, reflecting the greater illumination demands at the rear position.