GMC Truck Dome Light Bulb Size

The GMC Truck dome light requires a unique bulb size of 94 for the interior lighting system. Data for the specified lighting component covers the range from 1956 to 1957.

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
1956-1957	94

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Dual-filament bulb with BAY15d bayonet base. Variant of 1157. 12V, 21/5W.	94

Other Locations

Additional Notes

The bulb size 94 is an ANSI-standard type recognized in both the United States and Canada, operating at 12 volts with a dual-filament design rated at 21/5 watts.
The 94 bulb uses a BAY15d bayonet base, a two-pin offset base style where the two pins are positioned at different heights to ensure correct orientation during installation.
The dual-filament construction of the 94 bulb means it contains two separate filaments within a single envelope, each serving a distinct function at different wattage levels.
The 94 bulb is classified as a variant of the 1157, indicating shared electrical and base characteristics with that widely used automotive bulb type, though the two are not necessarily interchangeable in all applications.
The GMC Truck dome light used the 94 bulb size across the 1956-1957 model years.