The Dodge Royal Monaco front side marker uses 1157NA and 168 bulb sizes, while the rear side marker requires a 168 bulb size. The replacement chart covers 1975 to 1977 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 Dodge Royal Monaco uses two distinct bulb types across its front and rear side marker positions: the 1157NA and the 168, both conforming to ANSI standards recognized in the United States and Canada.
The 168 is a miniature wedge bulb in the T10 form factor, operating at 12V with a 4.9W output. Its wedge base design means it requires no separate metal base, as the glass envelope itself acts as the retention mechanism within the socket.
The 1157NA 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 natural amber glass envelope gives it its "NA" designation, producing amber light without the need for a colored lens or separate filter.
The 168 bulb is the more widely used type across the Royal Monaco's side marker positions, appearing in both the front and rear side marker sockets for the 1975-1976 model years, as well as the rear side marker for 1977.
For the 1977 Dodge Royal Monaco, the front side marker position uses the 1157NA rather than the 168 used in prior years, making the front socket specification for that year incompatible with a direct 168 substitution. The BAY15d bayonet base of the 1157NA is physically different from the wedge base of the 168.
The dual-filament nature of the 1157NA means it carries separate circuits for two brightness levels within a single bulb. A single-filament replacement would not replicate this electrical behavior in applications where both filaments are utilized.
The 1157NA's natural amber glass is an integral part of its specification. A standard 1157 bulb with clear glass would not produce the same amber output and would not be a specification-equivalent substitute in the 1977 front side marker position of the Royal Monaco.
The rear side marker position on the Dodge Royal Monaco uses the 168 bulb across all three model years covered in the specifications, indicating a consistent socket type for that position throughout the 1975-1977 period.