Ford F-650 Dome Light Bulb Size

The Ford F-650 dome light requires bulb size 578 or 105 depending on the specific application. Data for the provided bulb sizes covers the range from 2000 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
2021-2022	578
2017-2019	578
2000-2003	105

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Festoon bulb, 41mm length, end-cap contacts. 12V, 12W.	578
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Variant of 1156. 12V, 13W.	105

Other Locations

Additional Notes

The Ford F-650 dome light draws from two distinct bulb types across its model years: the 578 festoon and the 105 single-filament bayonet.
The 578 bulb is a festoon type, meaning it is cylindrical in form and makes electrical contact through metal caps at both ends rather than through a base socket.
The 578 bulb measures 41mm in length and operates at 12V with a 12W output, conforming to ANSI standards recognized in both the US and Canada.
The Ford F-650 uses the 578 bulb for the dome light across the 2017-2019 and 2021-2022 model years.
The 105 bulb uses a BA15s bayonet base, a single-contact fitting that locks into its socket with a twist rather than a straight insertion.
The 105 is a variant of the 1156 bulb family, sharing the BA15s base, though it carries a single filament and operates at 12V with a 13W output.
The Ford F-650 uses the 105 bulb for the dome light across the 2000-2003 model years.
The 578 and 105 bulbs are not interchangeable, as they differ in both physical form and base type, with the 578 using end-cap contacts and the 105 using a bayonet mount.
Both the 578 and 105 bulbs conform to ANSI standards applicable in the US and Canada, placing them within a standardized North American classification system.
The one-watt difference between the 105 at 13W and the 578 at 12W reflects a minor variation in power draw between the two generations of dome light fitment.