GMC R3500 License Plate Bulb Size

The GMC R3500 license plate light requires bulb size 194 or 67 depending on the specific configuration of the vehicle. Data for the lighting components covers the range from 1987 through 1991.

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
1988-1991	194
1987	67

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Miniature wedge bulb (T10). 12V, 3.78W.	194
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Lower wattage variant of 1156. 12V, 8W.	67

Other Locations

Additional Notes

The GMC R3500 uses two distinct bulb types across its license plate bulb fitments: the 194 and the 67, each with different base designs and wattage ratings.
The 194 bulb is a T10 miniature wedge type, operating at 12V and 3.78W, and conforms to the ANSI standard applicable in both the US and Canada.
The T10 wedge base of the 194 bulb is a push-in design with no separate metal base, relying on the glass envelope itself to make contact with the socket.
The 67 bulb uses a BA15s single-contact bayonet base, operating at 12V and 8W, and also conforms to the ANSI standard for the US and Canada.
At 8W, the 67 bulb draws more than twice the wattage of the 194, which reflects a fundamental difference in socket and circuit design between the two fitment years.
The 67 bulb is described as a lower wattage variant of the 1156, meaning it shares the BA15s bayonet base but is not electrically interchangeable with the 1156 due to the wattage difference.
The GMC R3500 used the 67 bulb for the 1987 model year, while the 194 bulb applies to the 1988-1991 model years, indicating a socket change occurred between those production years.
Because the 194 uses a wedge base and the 67 uses a bayonet base, the two bulb types are physically incompatible with each other's sockets and are not interchangeable.