The Plymouth PB100 front turn signal uses bulb sizes 1157, 1157NA, or 1034NA, while the rear turn signal requires either 1157 or 198 size bulbs. The replacement chart covers 1975 through 1980 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 Plymouth PB100 front and rear turn signals draw from three distinct bulb types across the 1975-1980 model years: the 1157, the 1157NA, the 1034NA, and the 198.
The 1157 is a dual-filament bulb rated at 12V with a 21W high filament and a 5W low filament, mounted on a BAY15d bayonet base. Its dual-filament design allows it to serve both turn signal and running light functions from a single housing.
The 1157NA shares the same 12V, 21W/5W dual-filament construction and BAY15d bayonet base as the 1157, but its glass envelope is tinted natural amber. This tint produces an amber output without relying on a colored lens.
The 1034NA is described as a variant of the 1157. It carries the same BAY15d bayonet base, natural amber glass, and 12V, 21W/5W ratings, though it is catalogued under a separate ANSI designation.
The 198 is a miniature wedge bulb of the T5 form factor, rated at 12V and 2W. Unlike the 1157-series bulbs, it is a single-filament, low-wattage lamp with no bayonet base.
For the Plymouth PB100 front turn signal, the 1979-1980 model years use the standard 1157, while 1978 and 1976 use the amber-tinted 1157NA, 1977 uses the 1034NA, and 1975 uses the 198.
The front turn signal position shows variation across all six model years, with no single bulb type used consistently throughout the entire 1975-1980 span.
The rear turn signal on the PB100 uses the 198 wedge bulb for the 1975-1978 model years, then transitions to the 1157 for 1979-1980.
The 1157 and 1157NA share physical base compatibility through the BAY15d fitting, but substituting a clear 1157 for an 1157NA in a position that relies on the bulb's amber glass to meet color output requirements would alter the signal color.
The 198 wedge bulb is not interchangeable with any of the 1157-series bulbs, as it differs in base type, wattage, filament count, and physical form factor.