Peterbilt 337 headlight bulbs utilize a 9007 size for both high beam and low beam applications. The replacement chart covers vehicle production spanning 2010 to 2017 with corresponding bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 9007 bulb is the sole headlight bulb type specified for the Peterbilt 337 across all listed model years.
The 9007 bulb type is used for both the high beam and low beam headlight positions in the Peterbilt 337 (2010-2017), meaning a single bulb serves dual-beam functions within one housing unit.
The 9007 is a dual-filament bulb, with one filament dedicated to high beam output and a separate filament dedicated to low beam output, which is what allows it to fulfill both roles simultaneously.
The 9007 bulb operates on a standard halogen platform, producing light through a tungsten filament enclosed in a halogen gas-filled quartz envelope.
The 9007 bulb uses an asymmetric filament arrangement, where the high beam filament is positioned differently from the low beam filament to produce distinct beam patterns for each function.
The 9007 bulb base uses a three-pronged connector configuration, which is not interchangeable with visually similar dual-filament types such as the 9004, despite their comparable appearance.
The 9007 and 9004 bulbs share a similar physical form but differ in their high and low beam filament polarity assignments, making cross-substitution result in reversed beam behavior if attempted.
The consistent use of the 9007 across the 2010-2017 model range indicates that replacement bulbs sourced for any year within that span are fitment-compatible with all other years listed.