The White/GMC WAH uses 1157 bulb size for both front and rear turn signal applications. Replacement chart data covers 1990 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 1157 is the sole bulb type specified for the White/GMC WAH across all listed turn signal positions for model years 1990-1995.
The 1157 is a dual-filament bulb, meaning it contains two separate filaments within a single envelope, one rated at 21W and one at 5W.
It operates on a 12-volt electrical system, which is standard for automotive applications of this era.
The 1157 uses a BAY15d bayonet base, a two-pin offset base design that prevents incorrect insertion by ensuring the pins are not symmetrically placed.
The 1157 conforms to ANSI standards and is recognized in both the United States and Canada, reflecting broad regional availability.
Both the front and rear turn signal positions on the WAH share the same 1157 specification across all six model years listed, indicating a uniform fitment across the vehicle.
Because the BAY15d base has offset pins, it is not interchangeable with single-pin bayonet bases such as the BA15s, which is used on single-filament bulbs like the 1156.