The H6054 is an ANSI-standardized 5x7-inch rectangular sealed beam unit operating at 12 volts, in which the lens, reflector, and filament are fused into a single non-serviceable assembly, meaning the entire unit is replaced rather than an internal bulb.
The GMC B7 uses the H6054 for both high beam and low beam headlight positions across the 1996-2002 model years, with no distinction between the two functions in terms of bulb type.
Because both beam positions share the same H6054 specification, the sealed beam unit serves a dual-function role rather than relying on separate dedicated bulbs for each lighting mode.
The H6054 sealed beam format is an ANSI-recognized standard applicable in both the United States and Canada, which reflects a period of headlight regulation that mandated standardized replaceable sealed beam units rather than proprietary housings.
The 5x7-inch rectangular form factor of the H6054 is a specific physical standard, and substituting a unit of a different size or shape would result in an incompatible fitment regardless of voltage or wattage ratings.