Avanti II Map Light Bulb Size

The Avanti II map light requires bulb sizes 57 and 257 for the interior illumination system. Available information covers the period from 1965 through 1973 for the specified vehicle components.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Bulb Size by Year Range

Years	Bulb Size
1973	57
1969-1972	257
1968	57
1965-1967	257

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Single-filament bulb with BA9s base. 12V, 1W.	57
ANSI standard (US & Canada). Festoon or BA9s base instrument bulb. 12V, 2W.	257

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Additional Notes

The Avanti II map light draws from two ANSI-standardized bulb types across its 1965-1973 model years: the 57 and the 257.
The 257 bulb operates at 12 volts and consumes 2 watts, making it the higher-wattage of the two types specified for this application.
The 57 bulb operates at 12 volts but consumes only 1 watt, and it uses a BA9s base with a single filament.
The 257 bulb is available in either a festoon or BA9s base configuration, which means the base type is not fixed to a single form factor for that part number.
The 257 was the specified map light bulb for the Avanti II across 1965-1967 and 1969-1972, representing the majority of the production years covered in these specifications.
The 57 bulb was specified for the 1968 and 1973 model years, making its fitment non-consecutive across the production run.
Because the 57 and 257 share the BA9s base as a common option, physical interchangeability in the socket is possible, but their wattage ratings differ and the two are not designated as interchangeable within these specifications.
Both bulb types carry ANSI standardization applicable to the US and Canadian markets.