The Chevrolet Townsman front and rear turn signal bulbs both utilize a 1157 size bulb. The replacement chart covers vehicle production spanning 1969 to 1972.
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 Chevrolet Townsman across all listed turn signal positions and model years.
The 1157 is a dual-filament bulb, meaning it contains two separate filaments within a single envelope, allowing it to serve two distinct lighting functions from one unit.
It operates on a 12-volt electrical system and carries a wattage rating of 21W on the high filament and 5W on the low filament, corresponding to its active and standby lighting states respectively.
The 1157 uses a BAY15d bayonet base, a two-pin offset base design that physically prevents incorrect insertion by positioning the two pins at different heights along the base.
The 1157 conforms to ANSI standards and is recognized in both the United States and Canada, placing it within a widely adopted North American specification framework.
The Chevrolet Townsman (1969-1972) uses the same 1157 bulb for both the front and rear turn signal positions, indicating no differentiation in bulb type between the two locations.
Because the front and rear turn signals share the same bulb specification across all four model years, the 1157 is interchangeable between those positions on this vehicle.
The BAY15d bayonet base is a keyed fitment, so bulbs with a standard single-pin or symmetrical two-pin bayonet base are not compatible replacements, even if their wattage ratings are similar.