The Ford F-550 Super Duty parking light utilizes 7444NA, 3157NA, 4157, and 3157 bulb sizes depending on the specific vehicle configuration. Available data for the mentioned components covers a range from 1999 through 2019.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 3157NA bulb is the most frequently specified front parking light bulb across the Ford F-550 Super Duty's model history, covering 2011-2016 as a standalone fitment and appearing alongside the 4157 as a conditional fitment for halogen capsule headlamp configurations in 2006-2010.
The 3157NA is an ANSI-standard dual-filament wedge bulb in the T25 form factor, rated at 12V with a 27W high-filament and 7W low-filament draw. Its "NA" designation indicates natural amber glass, which produces an amber output without the use of an amber-tinted lens.
The 4157 shares the same T25 form factor, dual-filament design, and 12V/27W/7W electrical rating as the 3157NA, but lacks the natural amber glass coating. On the F-550 Super Duty, it was specified exclusively for sealed beam headlamp configurations in 2006-2010.
The 3157 is electrically and physically identical to the 4157, also rated at 12V/27W/7W in a T25 dual-filament wedge body without amber glass. It served as the front parking light bulb from 1999-2005 in sealed beam headlamp configurations and as the sole fitment from 1999-2003.
Because the 3157NA, 4157, and 3157 share the same T25 wedge base and identical wattage ratings, their physical interchangeability is high, though substituting a clear bulb for an NA-coded one may affect the amber color output required by lighting regulations in certain jurisdictions.
The 7444NA is a T20 dual-filament wedge bulb rated at 12V/21W/5W with natural amber glass. Its lower wattage compared to the T25-family bulbs means it is not a direct electrical substitute for the 3157NA, 4157, or 3157, despite sharing the same amber glass characteristic as the 3157NA.
On the Ford F-550 Super Duty, the 7444NA was specified for 2017-2019 models equipped with halogen capsule headlamps, and again as the sole fitment for the 2022 model year, making it the most recent bulb type in the specifications.
The 12961 is a Philips part number designating a single-filament T10 miniature wedge bulb with a W2.1x9.5d base, rated at 12V/5W. Its single-filament design and significantly lower wattage distinguish it from all other bulbs in these specifications, and it was the specified fitment solely for the 2021 model year.
The W2.1x9.5d base of the 12961 is physically incompatible with the wedge bases used by the T20 and T25 bulbs in these specifications, meaning the 12961 is not interchangeable with any other bulb type listed for the F-550 Super Duty's front parking light position.
For 2004-2005 model years, the F-550 Super Duty used the 3157NA with halogen capsule headlamps and the 3157 with sealed beam headlamps, representing the only years where both bulb variants appeared without the 4157 being involved in the sealed beam configuration.