The Dodge D450 front turn signal uses 1157 or 199 bulb sizes, while the rear turn signal requires 1157 or 198 bulb sizes. The replacement chart covers 1978 through 1981 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 most frequently specified bulb across the Dodge D450 turn signal data, covering both front and rear positions for the 1979-1981 model years.
The 1157 is a dual-filament bulb rated at 12V with a 21W main filament and a 5W secondary filament, mounted on a BAY15d bayonet base, which allows it to serve both signaling and running light functions within a single housing.
The BAY15d base features two offset pins at different heights, a design that prevents incorrect insertion and distinguishes it from single-filament bayonet bases.
For the 1978 Dodge D450, the front turn signal uses the 199 bulb rather than the 1157 used in later years.
The 199 is a single-filament bulb rated at 12V and 21W, fitted with a BA15s bayonet base, and is classified as a variant of the 1156 bulb type.
Because the 199 uses a BA15s base and the 1157 uses a BAY15d base, these two bulb types are not directly interchangeable despite sharing a similar voltage and wattage range.
The 1978 rear turn signal on the Dodge D450 uses the 198 bulb, a miniature wedge type in the T5 form factor rated at 12V and 2W.
At 2W, the 198 bulb operates at a significantly lower power level than either the 1157 or the 199, reflecting a different circuit and socket design in the 1978 rear turn signal position.
The T5 wedge base of the 198 bulb is physically incompatible with the bayonet sockets used by the 1157 and 199 bulbs, making cross-substitution between these types impossible without socket modification.
All three bulb types specified for the Dodge D450 conform to ANSI standards applicable in both the United States and Canada.