Dodge B2500 Dome Light Bulb Size

The Dodge B2500 dome light requires bulb size 578 or 906 depending on the specific configuration of the interior lighting. Data for the bulb sizes covers the range from 1995 to 1998.

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
1998	578
1995-1996	906

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Festoon bulb, 41mm length, end-cap contacts. 12V, 12W.	578
ANSI standard (US & Canada). Miniature wedge bulb (T10). 12V, 8W.	906

Other Locations

Additional Notes

The 578 and 906 are both ANSI-standardized bulb types recognized across the United States and Canada, meaning they conform to established electrical and physical specifications rather than being proprietary to a specific vehicle manufacturer.
The 578 is a festoon-style bulb measuring 41mm in length with end-cap contacts, operating at 12 volts and 12 watts. Its end-cap design means electrical contact is made at each end of the bulb body rather than through a base pin or wedge.
The 906 is a T10 miniature wedge bulb, operating at 12 volts and 8 watts. The wedge base design uses the glass envelope itself, pinched at the bottom, to secure the bulb and make electrical contact without a separate metal base.
The 578 draws 12 watts while the 906 draws 8 watts. These two bulb types are not interchangeable, as they differ in both physical form and wattage.
The Dodge B2500 uses the 906 bulb for the dome light in the 1995-1996 model years, and the 578 bulb in the 1998 model year, indicating a change in dome light socket design between those production periods.
Because the 578 uses end-cap contacts and the 906 uses a wedge base, the two bulb types require physically different sockets and cannot be substituted for one another regardless of voltage compatibility.