Chevrolet Tiltmaster (W-Series) Headlight Bulb Size

Additional Notes

• The Chevrolet Tiltmaster (W-Series) headlight specifications reference three sealed beam form factors across its model years: 4x6-inch rectangular units, square 4-inch units, and round units in 5.75-inch and 7-inch sizes. All are 12V sealed beam assemblies conforming to ANSI standards recognized in both the United States and Canada.
• Sealed beam units, by design, house the filament, reflector, and lens within a single fused glass enclosure. When a filament fails, the entire unit requires replacement rather than an internal bulb swap. This applies to every headlight position across all listed model years of the Tiltmaster (W-Series).
• The H4651 and H4656 are both 4x6-inch rectangular sealed beam units sharing the same physical housing format, yet they serve distinct functions. The H4651 is designated for the high beam position, while the H4656 serves the low beam position. Despite their similar form factor, these two types are not interchangeable due to differing filament configurations and beam patterns.
• The H4652, used as the low beam unit for the 1997-2000 model years, is a variant of the H4651 in the same 4x6-inch rectangular format. Its classification as a variant indicates a functional distinction from the H4651, and the two are not listed as interchangeable within these specifications.
• For the 1992-1996 model years, the high beam position uses the H5001, a 4-inch square sealed beam unit, while the low beam position uses the H5006, a 5.75-inch round sealed beam unit. The use of two different form factors for high and low beams in the same model year means the two positions require separate, non-interchangeable units.
• The 1986-1988 model years present a configuration-dependent fitment. Vehicles equipped with a two-headlamp system use the H6024, a 7-inch round sealed beam unit, for both high and low beam positions. Vehicles equipped with a four-headlamp system use the H4651 for high beam and the H4656 for low beam. Selecting the correct unit therefore requires confirming the headlamp count of the specific vehicle.
• The H6024 is the only unit in these specifications rated for dual-function use, covering both high and low beam positions within the two-headlamp configuration of the 1986-1988 model years. All other bulb types in the specifications are assigned to a single beam function only.
• Across the 1997-2001 model years, the high beam position standardized on the H4651, while the low beam position transitioned from the H4652 to the H4656 between the 2000 and 2001 model years. These two low beam types share the same 4x6-inch rectangular format but carry separate ANSI designations, indicating they are distinct parts.