GMC P60 Headlight Bulb Size

Additional Notes

• The GMC P60 uses sealed beam headlight units across all listed model years (1983-1990), meaning the entire lens-and-filament assembly is replaced as one unit rather than swapping an internal bulb.
• All sealed beam types specified for the P60 conform to ANSI standards recognized in both the United States and Canada, and all operate at 12 volts.
• The H6054 is a 5x7-inch rectangular sealed beam unit that serves as both the high beam and low beam source on two-rectangular-headlamp configurations, as a single unit handles both functions.
• The H6024 is a 7-inch round sealed beam unit fitted to P60 models equipped with two round headlamps, covering both high and low beam positions with the same part number.
• On four-rectangular-headlamp configurations, the H4651 and H4656 are not interchangeable despite sharing the same 4x6-inch rectangular form factor. The H4651 is designated for the high beam position, while the H4656 is designated for the low beam position.
• The 1984 GMC P60 is a notable fitment case, as its two-headlamp configuration lists only the H6054 without a round-headlamp variant, unlike the 1983 and 1985-1988 model years which include an H6024 round-headlamp option.
• The 1989-1990 P60 models list only the H6054 for both high and low beam positions, with no headlamp-configuration qualifiers, indicating a single headlamp system for those years.
• Because the H4651 and H4656 share the same physical size, installing the wrong unit in a four-lamp system would place an incorrect beam pattern in a given position, making position-specific selection critical for four-rectangular-headlamp P60 configurations from 1983-1988.