The GMC C2500 Suburban brake light utilizes 3057, 2057, and 1157 bulb sizes depending on the specific production period for the vehicle. Data provided covers the span from 1979 through 1999 for the various components listed.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The GMC C2500 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 is the most widely specified brake bulb across the C2500 Suburban lineup, covering the 1992-1999 model years.
The 3057 is a dual-filament wedge bulb in a T25 form factor, rated at 12V with a 27W high filament and 7W low filament, conforming to ANSI standards for the US and Canadian markets.
The 2057 was specified for the 1983-1986 model years and uses a BAY15d bayonet base, a two-pin offset base design that physically locks the bulb in place with a twist.
The 2057 operates at 12V with filaments rated at 26.9W and 8W, making it a higher-output variant of the 1157 despite sharing the same BAY15d base type.
Because the 2057 and 1157 share the BAY15d bayonet base, the two bulbs are physically interchangeable in socket fitment, though their wattage outputs differ.
The 1157 was specified for the GMC C2500 Suburban from 1979-1982, rated at 12V with filaments at 21W and 5W, making it the lowest-output dual-filament brake bulb in these specifications.
The 921 is a single-filament T15 wedge bulb rated at 12V and 16W, specified exclusively for the center high mount stop light on 1993-1997 model years.
The T25 and T15 designations on the 3057 and 921 respectively refer to the bulb's tubular form factor, with the numeric suffix indicating width in units of one-eighth of an inch.
All four bulb types in these specifications conform to ANSI standards applicable in both the United States and Canada.