Detail Specification Part Number 540 (TUNG-SOL Corp.) Part Type Vintage Heavy-Duty Thermal Turn Signal Flasher Voltage 12V Terminals 2-Pin (Standard Flasher Post Style, typically marked \'X\' and \'L\') Load Type Thermal Flasher (Compatible with Incandescent bulbs only ) Lamp Load Capacity Heavy-Duty, Variable Load. Typically rated for $3$ to $6$ incandescent lamps, often used when a standard 552 flasher may experience \"running on\" or a slow flash rate due to increased lamp resistance/load (e.g., when adding lamps or on larger trucks/vans). Application Notes Used for the Turn Signal function on vehicles where a robust 2-pin 12V flasher is required. This part often cross-references to the more common aftermarket 552 specification flasher, but with a heavier-duty rating. Make Representative Models (Turn Signal Function) Representative Years General Motors (GM) C/K Series Pickups, G-Series Vans, Impala, Chevelle, Camaro, Nova ~1956-1981 Ford F-Series Pickups, Econoline Vans, Mustang, Galaxie, Fairlane ~1950s-1980s Chrysler / Mopar Dodge Trucks (D Series), Plymouth, Dodge, Chrysler Passenger Cars ~1950s-1980s AMC / Jeep Gremlin, Hornet, Javelin, CJ Series Trucks/SUVs ~1960s-1980s
