Peterbilt 378 License Plate Bulb Size

The Peterbilt 378 license plate component utilizes bulb sizes 67 and 97 for illumination purposes. Available information covers the specific range of years from 1988 through 2007.

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
1998-2007	67
1988-1997	67
1988-1997	97 (With Halogen Capsule Headlamps)

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Lower wattage variant of 1156. 12V, 8W.	67
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Variant of 1156. 12V, 13W.	97

Other Locations

Additional Notes

The Peterbilt 378 uses the bulb 67 as its license plate bulb across the full span of model years covered in the specifications, from 1988 to 2007.
The bulb 67 is an ANSI-standardized single-filament bulb rated at 12V and 8W, fitted with a BA15s bayonet base, and is recognized for use in both the United States and Canada.
The bulb 97 is also an ANSI-standardized single-filament bulb with a BA15s bayonet base, rated at 12V and 13W, making it a higher-wattage variant within the same base family as the 67.
For the Peterbilt 378 model years 1988-1997, vehicles equipped with halogen capsule headlamps take the bulb 97 rather than the bulb 67 for the license plate position.
From 1998 onward through 2007, the specifications list only the bulb 67, with no halogen capsule headlamp variant noted for those years.
Although the 67 and 97 share the same BA15s bayonet base, their wattage ratings differ by 5W, and the headlamp configuration of the vehicle determines which of the two is the correct fitment for 1988-1997 models.
The BA15s bayonet base is a single-contact base, which is consistent with the single-filament construction of both the 67 and the 97.
The 67 is described as a lower-wattage variant of the 1156 bulb, and the 97 is described as a variant of the 1156 as well, placing both within the same broad bulb family despite their different wattage ratings.