The White/GMC WCL uses a 1157 bulb size for front side marker applications and a 194 bulb size for rear side marker positions. The replacement chart covers 1988 to 1993 model 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 WCL uses the 1157 bulb for the front side marker position across the 1988-1993 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 WCL uses the 194 bulb across the same 1988-1993 model years.
The 194 is a single-filament miniature wedge 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, making the two bulb types non-interchangeable between the front and rear side marker positions.
The significant wattage difference between the 1157 (21W on its primary filament) and the 194 (3.78W) reflects their respective roles, with the front marker drawing considerably more power than the rear.
Both the 1157 and 194 operate on a 12V electrical system, consistent with standard automotive electrical architecture.