The White/GMC WX front side marker bulb uses a 1157 size, while the rear side marker bulb uses a 194 size. The replacement chart covers vehicle production years from 1988 to 1995 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 WX uses the 1157 bulb for the front side marker position across the full 1988-1995 model range.
The 1157 is a dual-filament bulb with a BAY15d bayonet base, rated at 12V and carrying two wattage ratings of 21W and 5W, corresponding to its two filaments.
The BAY15d bayonet base features offset pins, a physical characteristic that prevents incorrect single-filament bulbs from being seated in its place.
The rear side marker position on the WX calls for the 194 bulb across the same 1988-1995 span.
The 194 is a single-filament miniature wedge bulb in the T10 form factor, rated at 12V and 3.78W, making it significantly lower in output than the 1157 used at the front.
Both the 1157 and 194 conform to ANSI standards recognized in the United States and Canada, meaning they follow standardized electrical and physical specifications within those markets.
The front and rear side marker positions on the WX require different bulb types, and the two are not interchangeable due to differences in base type, wattage, and filament count.
The wedge base of the 194 is retained by friction within its socket, whereas the 1157 uses a twist-lock bayonet mechanism, further distinguishing the two fitments.