Ford F-450 Super Duty Back Up Light Bulb Size

The Ford F-450 Super Duty back up light utilizes bulb sizes WT21W, 3157, 7440, 921, 2356, 2456, and 3156. Available data for the specified components covers the range from 1999 to 2022.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Bulb Size by Year Range

Years	Bulb Size
2020-2022	WT21W
2019	3157
2017-2018	7440
2011-2016	921
2010	2356
2007-2009	2456
2006	2356
2001-2005	2456
2000	3156
1999	2356

Bulb Specifications

Description	Bulb Size
Ford OEM part. Single-filament wedge bulb (T20). Originally used in 2021+ Ford F-150, Bronco, and Maverick. 12V, 21W.	WT21W
ANSI standard (US & Canada). Dual-filament wedge bulb (T25). 12V, 27W/7W.	3157
ANSI standard (US & Canada). Single-filament wedge bulb (T20). 12V, 21W.	7440
ANSI standard (US & Canada). Wedge bulb (T15). 12V, 16W.	921
ANSI standard (US & Canada). Dual-filament bulb with BAY15d bayonet base. 12V.	2356
ANSI standard (US & Canada). Festoon bulb, specialty application. 12V.	2456
ANSI standard (US & Canada). Single-filament wedge bulb (T25). 12V, 27W.	3156

Other Locations

Additional Notes

The Ford F-450 Super Duty backup light specifications span model years 1999 through 2022, covering a total of nine distinct bulb sizes across that period.
The 2456 bulb is the most frequently specified size across the F-450 Super Duty's history, appearing in nine model years: 2001-2005, 2007-2008, and 2003-2004. It is an ANSI-standard festoon bulb rated at 12V and designated for specialty applications.
The WT21W is a Ford OEM part rather than an ANSI-standard bulb. It is a single-filament T20 wedge bulb rated at 12V and 21W, specified for the 2020-2022 F-450 Super Duty. This bulb originated in the 2021-and-later Ford F-150, Bronco, and Maverick.
The 921 bulb, a T15 wedge rated at 12V and 16W, is specified for the 2011-2016 F-450 Super Duty, making it the longest consecutive run of a single bulb size in these specifications.
The 7440 and WT21W are both single-filament T20 wedge bulbs rated at 12V and 21W, yet they are not interchangeable. The WT21W is a Ford OEM part, while the 7440 is an ANSI-standard bulb, and the two are specified for different model years.
The 3157, specified for the 2019 F-450 Super Duty, is a dual-filament T25 wedge bulb rated at 12V with a 27W main filament and a 7W secondary filament. Its dual-filament design distinguishes it from the single-filament 3156, which was specified for the 2000 model year.
The 2356 bulb uses a BAY15d bayonet base rather than a wedge or festoon mount, setting it apart from most other bulbs in these specifications. It is an ANSI-standard dual-filament bulb rated at 12V and was specified for the 1999, 2006, and 2010 F-450 Super Duty.
The 2456 and 2356 bulbs share the same 12V rating and both carry ANSI-standard designations, but they differ in base type: the 2456 is a festoon bulb while the 2356 uses a BAY15d bayonet base, making them physically incompatible with each other's sockets.
The T25 platform is represented by two separate bulbs in these specifications: the dual-filament 3157 and the single-filament 3156. Although both share the same T25 wedge form factor, their filament configurations differ, which affects their compatibility in backup light sockets designed for a specific wattage draw.
Across the 2017-2022 model years, the F-450 Super Duty transitioned through three different bulb sizes: the 7440 (2017-2018), the 3157 (2019), and the WT21W (2020-2022), indicating that no single bulb size carried over continuously through that period.