Ford F-250 Super Duty front side marker bulbs use 12961 or 194 size, while rear side marker bulbs use 3157 or 12961 size. The replacement chart covers 1999 through 2023 production years with corresponding bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Ford F-250 Super Duty front side marker position uses two distinct bulb sizes across its model year range. The 12961 bulb covers 2011-2023, while the 194 bulb covers 1999-2010.
The 12961 is a Philips part number designating a T10 miniature wedge bulb with a W2.1x9.5d base, rated at 12V and 5W. The 194 is an ANSI-standard T10 miniature wedge bulb rated at 12V and 3.78W. Both share the T10 form factor, though their wattage and base designations differ.
For the 2017-2020 Ford F-250 Super Duty, the 12961 front side marker fitment carries a "With Halogen Capsule Headlamps" condition, indicating the specification applies specifically to that headlamp configuration.
The rear side marker position is dominated by the 3157 bulb, which appears across 1999-2006 and again from 2011-2023.
The 3157 is an ANSI-standard T25 dual-filament wedge bulb rated at 12V with a 27W/7W output. Its dual-filament design distinguishes it from the single-filament T10 bulbs used at the front.
The rear side marker for 2007-2010 uses the 12961 bulb rather than the 3157, representing a departure from the T25 dual-filament type used in surrounding model years at that position.
As with the front position, the rear side marker specifications for 2017-2020 carry the "With Halogen Capsule Headlamps" condition on the 3157 fitment.
The 3157 and 12961 are not interchangeable. The 3157 uses a T25 wedge base with dual filaments, while the 12961 uses a T10 wedge base with a single filament, making physical and electrical compatibility between the two incompatible.
The 194 and 12961 share the T10 wedge form factor but differ in wattage, with the 194 rated at 3.78W and the 12961 at 5W. Direct substitution between them may not be appropriate without confirming socket and circuit compatibility.
Across both marker positions, the 3157 is the most frequently specified bulb in the dataset, appearing in the rear side marker position for the majority of the model year range covered.