The Buick LaCrosse parking light utilizes bulb sizes 7443NA, 7444NA, 3757NA, 5702AK, and 4157NA. Available information covers the specific range from 2005 through 2016 for the components listed.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 4157NA is a dual-filament T25 wedge bulb rated at 12V with a 27W/7W output split, where the higher wattage filament serves the brighter function and the lower wattage filament serves the parking or running light function.
The Buick LaCrosse front parking light used the 4157NA across the 2005-2008 model years, making it the most consistently specified bulb in these listings.
The "NA" suffix in bulb designations such as 4157NA, 7443NA, and 3757NA indicates natural amber glass, meaning the amber color is produced by the glass itself rather than by a coating applied over clear glass.
The 3757NA is a T25 dual-filament wedge bulb running at 12V, and it was specified for the LaCrosse front parking light across the 2010-2013 model years.
The 7443NA and 7444NA are both T20 dual-filament wedge bulbs rated at 12V and 21W/5W, though they carry different ANSI designations and were each specified for a single model year, 2016 and 2014-2015 respectively.
The T25 and T20 designations refer to the physical size of the wedge base, with T25 being larger than T20. Bulbs of different base sizes are not interchangeable even when their electrical ratings are similar.
The 5702AK is a Sylvania-specific part number for a variant of the ANSI 3157 bulb with an amber coating rather than natural amber glass, and it was the specified front parking light bulb for the 2009 LaCrosse.
Because the 5702AK uses an amber coating over clear glass while the 3757NA uses natural amber glass, the two bulbs produce amber light through different methods despite both being dual-filament T25 wedge types at 12V.
The 4157NA and 5702AK share the same 27W/7W power rating and T25 form factor, but the 4157NA uses natural amber glass while the 5702AK uses a coated finish, which affects light output characteristics.
All bulbs listed across these specifications conform to ANSI standards applicable in both the United States and Canada, indicating regulatory compliance for use in North American vehicles.