The Opel Manta front and rear turn signal bulbs utilize either 1157 or 1034 size specifications. The replacement chart covers 1971 through 1975 production years with corresponding bulb size data.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Opel Manta uses two distinct bulb types across its 1971-1975 model years for turn signal applications: the 1034 and the 1157, both governed by ANSI standards applicable in the US and Canada.
Both the 1034 and 1157 are dual-filament bulbs, meaning each serves two separate lighting functions within a single housing, operating on a shared 12V electrical system.
The 1157 operates at 21W on its primary filament and 5W on its secondary filament, a configuration typical of combined turn signal and parking light applications.
The 1034 shares the same 21W/5W power rating and BAY15d bayonet base as the 1157, and is formally classified as a variant of it under ANSI standards.
Despite their technical similarities, the 1034 and 1157 are not confirmed as interchangeable in these specifications, and substituting one for the other without verification carries fitment risk.
Both bulb types use the BAY15d bayonet base, a double-contact offset-pin base design that physically prevents incorrect single-filament bulbs from being seated in the socket.
The Opel Manta (1973-1975) uses the 1157 bulb for both front and rear turn signals, representing a consistent specification across those three model years.
The 1971-1972 model years specify the 1034 for both front and rear turn signals, with the bulb type change occurring between the 1972 and 1973 model years.