The White/GMC ACL uses a 1157 bulb size for front side marker applications and a 194 bulb size for rear side marker installations. The replacement chart covers 1988 to 1995 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 White/GMC ACL uses the 1157 bulb for the front side marker position across the 1988-1995 model years.
The 1157 is a dual-filament bulb with a BAY15d bayonet base, rated at 12V with a 21W/5W output, and conforms to ANSI standards recognized in both the United States and Canada.
The dual-filament design of the 1157 means it carries two separate tungsten filaments within a single envelope, allowing it to serve two distinct lighting functions at different wattages.
The rear side marker position on the White/GMC ACL takes the 194 bulb across the same 1988-1995 model years.
The 194 is a miniature wedge-type bulb in the T10 form factor, rated at 12V and 3.78W, also conforming to ANSI standards for the United States and Canada.
The wedge base of the 194 differs fundamentally from the BAY15d bayonet base of the 1157, meaning the two bulb types are not interchangeable between the front and rear side marker positions.
The 194 operates at 3.78W, which is substantially lower than either filament rating of the 1157, reflecting the reduced output typical of small marker and clearance lighting applications.
The BAY15d base of the 1157 features offset pins that prevent incorrect single-filament substitutes from seating properly, which is a built-in safeguard against mismatched replacements in that socket.