Peterbilt 372 Headlight Bulb Size

The Peterbilt 372 headlight bulb specifications include high beam sizes H6054, 9004, and H4651, along with low beam sizes H6054, 9004, and H4652 in various bulb configurations. The replacement chart covers 1989 through 1995 production years with corresponding bulb size data.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

High Beam Headlight

Years	Bulb Size
1989-1995	H6054 (With 2 Rectangular Headlamps)
	H4651 (With 4 Rectangular Headlamps)
	H5001 (With 4 Round Headlamps)
	9004 (With Halogen Capsule Headlamps)

Low Beam Headlight

Years	Bulb Size
1995	H6054 (With 2 Rectangular Headlamps)
	H4652 (With 4 Rectangular Headlamps)
	H5006 (With 4 Round Headlamps)
	9004 (With Halogen Capsule Headlamps)
1990-1994	H6054 (With 2 Rectangular Headlamps)
	H4656 (With 4 Rectangular Headlamps)
	H5006 (With 4 Round Headlamps)
	9004 (With Halogen Capsule Headlamps)
1989	H6054 (With 2 Rectangular Headlamps)
	H4652 (With 4 Rectangular Headlamps)
	H5006 (With 4 Round Headlamps)
	9004 (With Halogen Capsule Headlamps)

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). 5x7-inch rectangular sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H6054
ANSI standard (US & Canada). 4x6-inch rectangular sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H4651
ANSI standard (US & Canada). 4-inch square sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H5001
ANSI standard (US & Canada). Dual-filament halogen bulb with P29t base. 12V, 65W/45W.	9004
ANSI standard (US & Canada). 4x6-inch rectangular sealed beam unit, variant of H4651. Not a replaceable bulb — the entire unit is replaced. 12V.	H4652
ANSI standard (US & Canada). 5.75-inch round sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H5006
ANSI standard (US & Canada). 4x6-inch rectangular sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H4656

Other Locations

Additional Notes

The Peterbilt 372 (1989-1995) was offered with four distinct headlamp configurations: two rectangular headlamps, four rectangular headlamps, four round headlamps, and halogen capsule headlamps. Each configuration requires a different bulb type, and the correct fitment is determined entirely by which headlamp assembly is installed on the vehicle.
The H6054 is a 5x7-inch rectangular sealed beam unit operating at 12V. It serves as both the high beam and low beam source in the two-rectangular-headlamp configuration, meaning a single unit handles both functions rather than separate bulbs for each beam mode.
The 9004 is the only non-sealed-beam bulb type in these specifications. It is a dual-filament halogen bulb with a P29t base, rated at 12V with 65W on high beam and 45W on low beam. Its single-bulb, dual-filament design means one unit covers both beam functions in the halogen capsule headlamp configuration.
Sealed beam units, including the H6054, H4651, H4652, H4656, H5001, and H5006, are not serviceable at the bulb level. When one of these units fails, the entire assembly is replaced rather than an internal component.
The four-rectangular-headlamp configuration uses different bulb types for high and low beams. The H4651 handles high beam duty across 1989-1995, while the low beam position uses the H4652 in 1989 and 1995, and the H4656 in 1990-1994. All three are 4x6-inch rectangular sealed beam units operating at 12V.
The four-round-headlamp configuration separates high and low beam functions between two distinct sealed beam units. The H5001, a 4-inch square sealed beam unit, covers high beam, while the H5006, a 5.75-inch round sealed beam unit, covers low beam. This pairing remains consistent across all model years in the specifications.
All bulb and sealed beam types listed across these specifications are built to ANSI standards recognized in both the United States and Canada, placing them within a standardized sizing and performance framework common to North American automotive lighting.
The low beam fitment for the four-rectangular-headlamp configuration shows a variation between model years: the H4652 appears in 1989 and 1995, while the H4656 is specified for 1990-1994. Both are 4x6-inch rectangular sealed beam units at 12V, but they carry distinct part designations and are not listed as interchangeable within these specifications.