Mack F Headlight Bulb Size

Mack F headlight bulbs utilize H6024, H4651, and H5001 sizes for high beam applications, while low beam configurations employ H6024, H4652, and H5006 bulb sizes. The replacement chart covers 1981 to 1982 production years 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.

High Beam Headlight

Years	Bulb Size
1981-1982	H6024 (With 2 Round Headlamps)
	H4651 (With 4 Rectangular Headlamps)
	H5001 (With 4 Round Headlamps)

Low Beam Headlight

Years	Bulb Size
1981-1982	H6024 (With 2 Round Headlamps)
	H4652 (With 4 Rectangular Headlamps)
	H5006 (With 4 Round Headlamps)

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). 7-inch round sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H6024
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). 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

Other Locations

Additional Notes

The Mack F covers the 1981-1982 model years in these specifications, and across both years the headlamp system varies by configuration: two round headlamps, four rectangular headlamps, or four round headlamps, each requiring a distinct set of bulb sizes for high and low beam functions.
All bulb types listed, H6024, H4651, H5001, H4652, and H5006, are sealed beam units built to ANSI standards recognized in both the United States and Canada. In a sealed beam design, the lens, reflector, and filament are fused into a single glass unit, meaning the entire assembly is replaced rather than an internal bulb.
The H6024 is a 7-inch round sealed beam unit operating at 12V. It serves as both the high beam and low beam unit in the two-round-headlamp configuration, meaning a single sealed beam type handles both functions in that setup.
The four-rectangular-headlamp configuration uses the H4651 for high beam and the H4652 for low beam. Both are 4x6-inch rectangular sealed beam units at 12V, with the H4652 defined as a variant of the H4651. These two types are not interchangeable despite their physical similarity, as each is rated for a specific beam function.
The four-round-headlamp configuration splits functions between the H5001 and H5006. The H5001 is a 4-inch square sealed beam unit used for high beam, while the H5006 is a 5.75-inch round sealed beam unit used for low beam. The two differ in both shape and size, making substitution between them incompatible.
Because the rectangular and round multi-lamp configurations use beam-specific sealed beam units, substituting a high beam unit in place of a low beam unit, or the reverse, would result in incorrect light output for that headlamp position.
The H6024, H4651, H5001, H4652, and H5006 are all 12V units, consistent with the standard 12-volt electrical systems found in commercial vehicles of this period.
The bulb fitment for the Mack F remained unchanged between 1981 and 1982 across all three headlamp configurations, with identical size codes listed for both model years in both high beam and low beam positions.