Peterbilt 320 Dome Light Bulb Size

The Peterbilt 320 dome light utilizes a specific bulb size identified as 97 for the interior illumination component within the cabin area of the heavy truck. Available information covers a continuous span of time starting from 1987 and ending in 1997 for the specified vehicle application.

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
1987-1997	97 (With 2 Rectangular Headlamps)

Bulb Specifications

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

Other Locations

Additional Notes

The Peterbilt 320 dome light uses the size 97 bulb across all specified model years from 1987-1997, exclusively on configurations equipped with 2 rectangular headlamps.
The 97 bulb follows ANSI standards recognized in both the United States and Canada, placing it within a regulated specification framework common to North American automotive lighting.
A single-filament design defines the 97 bulb, meaning it serves one lighting function rather than switching between two brightness levels as a dual-filament bulb would.
The 97 bulb uses a BA15s bayonet base, a single-contact mount where the bulb is inserted and twisted to lock into place rather than threaded.
At 12 volts and 13 watts, the 97 bulb operates within the standard low-voltage electrical system typical of commercial truck platforms.
The 97 bulb is a variant of the 1156, which shares the BA15s bayonet base but differs in wattage. The 1156 operates at a higher wattage, so the two are not directly interchangeable without accounting for that difference.
The headlamp configuration noted in the specifications, specifically 2 rectangular headlamps, functions as a fitment qualifier, indicating the dome light bulb size applies only to Peterbilt 320 units built with that particular headlamp arrangement.