American Motors Hornet front turn signal bulbs use 1157 or 1157NA size, while rear turn signal bulbs use 1157 size. The replacement chart covers 1970 through 1977 vehicle 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 bulb is the dominant type across the turn signal specifications for the American Motors Hornet, appearing in both front and rear positions across nearly the entire model range.
The 1157 is an ANSI-standard dual-filament bulb rated at 12V with a 21W high filament and a 5W low filament, mounted on a BAY15d bayonet base. The dual-filament design allows a single bulb to serve both turn signal and running light functions simultaneously.
The BAY15d bayonet base features two offset pins at different heights, a physical design that prevents incorrect insertion of a single-filament bulb into a dual-filament socket.
The 1157NA shares the same ANSI-standard electrical ratings and BAY15d base as the 1157, with the distinction that its glass envelope is natural amber rather than clear.
The 1157NA was specified exclusively for the front turn signal position on the 1970 Hornet, while the standard clear 1157 was used in the rear turn signal position for that same year.
The natural amber glass of the 1157NA produces an amber signal output without relying on a colored lens, which affects lens and housing compatibility relative to the clear 1157.
From 1971 onward, the front turn signal specification for the Hornet shifted from the 1157NA to the standard 1157, aligning the front and rear positions on a single bulb type through 1977.
Because the 1157 and 1157NA share identical base geometry and electrical ratings, the physical fitment is interchangeable, though substituting one for the other alters the color output at the lens depending on housing design.