Peterbilt 387 Headlight Bulb Size

Additional Notes

• The Peterbilt 387 (2000-2009) accommodates three distinct headlamp system configurations across its model range: a two-rectangular-headlamp setup, a four-rectangular-headlamp setup, and a halogen capsule headlamp setup. Each configuration requires a different bulb type for both high and low beam positions.
• The H6054 is a 5x7-inch rectangular sealed beam unit operating at 12V and conforming to ANSI standards applicable in the US and Canada. It serves as both the high beam and low beam bulb in the two-rectangular-headlamp configuration across all model years in the specifications, meaning a single unit type handles both functions in that setup.
• The 9004 is a dual-filament halogen bulb rated at 12V with a high beam output of 65W and a low beam output of 45W, fitted with a P29t base. Its dual-filament design allows one bulb to serve both the high and low beam positions in the halogen capsule headlamp configuration, consistent across all model years listed.
• The H4651, H4652, and H4656 are all 4x6-inch rectangular sealed beam units operating at 12V under ANSI standards. The H4652 is specifically noted as a variant of the H4651. These three types are not interchangeable without confirming the exact beam function and model year, as the specifications assign them to different beam positions and years within the four-rectangular-headlamp configuration.
• In the four-rectangular-headlamp configuration, the high beam position uses the H4651 across all model years from 2000-2009. The low beam position in that same configuration, however, varies by year, with the H4656 specified for 2000, 2005, and 2007-2009, and the H4652 specified for 2001-2004 and 2006.
• All sealed beam units in these specifications, including the H6054, H4651, H4652, and H4656, are replaced as complete assemblies rather than as individual replaceable bulbs. This is a fundamental distinction from the 9004 halogen capsule type, where only the bulb itself is replaced within the housing.
• The H4651 and H4656 share the same physical 4x6-inch sealed beam format and voltage rating, yet they are assigned to different beam functions within the four-rectangular-headlamp system. Substituting one for the other would not reflect the specifications and could affect beam pattern performance.
• All bulb types across the three headlamp configurations operate at 12V, which is consistent with standard automotive electrical systems. The only type in the specifications with a defined wattage rating is the 9004, at 65W for high beam and 45W for low beam.