The GMC K2500 Suburban brake light utilizes 3057, 2057, and 1157 bulb sizes depending on the specific production period. Provided information covers the full span from 1979 through 1999.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The GMC K2500 Suburban uses three distinct brake bulb types across its model years: the 3057, 2057, and 1157 for the main brake lights, and the 921 for the center high mount stop light.
The 3057 and 1157 are both dual-filament bulbs, meaning each serves two lighting functions from a single unit, typically combining stop and tail light operation within one bulb.
The 3057 is a T25 wedge-base bulb rated at 12V with filaments drawing 27W and 7W respectively, and it fits the GMC K2500 Suburban across the 1992-1999 model years.
The 1157 uses a BAY15d bayonet base and is rated at 12V with filaments drawing 21W and 5W, fitting the 1979-1982 model years.
The 2057 also uses a BAY15d bayonet base and shares the same base type as the 1157, though its filaments draw 26.9W and 8W, placing it between the 1157 and 3057 in output. It fits the 1983-1986 model years.
Because the 2057 and 1157 share the BAY15d bayonet base, they are physically interchangeable in terms of socket fit, though their wattage ratings differ and substitution may affect lighting output.
The 3057 uses a wedge base rather than a bayonet base, making it physically incompatible with the sockets designed for the 1157 or 2057 without modification.
The 921 is a single-filament T15 wedge bulb rated at 12V and 16W, used exclusively in the center high mount stop light position on the K2500 Suburban for the 1993-1997 model years.
All four bulb types conform to ANSI standards applicable in both the United States and Canada, indicating standardized electrical and physical specifications across those markets.
The center high mount stop light position on the K2500 Suburban uses a separate bulb type from the main brake lights, and the 921 is not interchangeable with any of the three bulbs used in the primary brake light positions.