The GMC Brigadier front side marker bulb uses either 194 or 1157 size, while the rear side marker bulb uses 1157 size. The replacement chart covers 1984 through 1988 production years with corresponding bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The GMC Brigadier Tiltmaster front side marker uses two distinct bulb types across the 1984-1988 model years, with the 194 and 1157 appearing in different years for the same position.
The 194 is a T10 miniature wedge bulb rated at 12V and 3.78W, conforming to the ANSI standard recognized in both the United States and Canada.
The 1157 is a dual-filament bulb with a BAY15d bayonet base, rated at 12V with a 21W/5W output, also conforming to the ANSI standard recognized in both the United States and Canada.
The dual-filament design of the 1157 means it operates two separate filaments at different wattages, a characteristic that distinguishes it functionally from the single-filament 194.
The BAY15d bayonet base of the 1157 features offset pins, which prevents it from being inserted in the same socket orientation as a standard single-filament bayonet bulb, making it physically non-interchangeable with single-filament bayonet types.
The 194 wedge base and the 1157 BAY15d bayonet base are mechanically incompatible socket types, so the two bulbs are not interchangeable with each other regardless of voltage.
The GMC Brigadier Tiltmaster front side marker for 1986-1985 uses the 1157, while the 1984 and 1987-1988 model years use the 194, indicating a non-sequential change in specification across the production run.
The rear side marker of the GMC Brigadier uses the 1157 consistently across the 1985-1988 model years.
The 1157 is shared between the front side marker position in 1985-1986 and the rear side marker position across 1985-1988, meaning the same bulb type serves both locations in those years.
The 194 at 3.78W draws considerably less power than the 1157 at 21W/5W, a difference that reflects the distinct electrical demands of each bulb type.