The 257 (Lionel number 2307-300) is the correct bulb for that car. 14.volts. My guess as to why they revised the bulb to 6 volts is the newer fire car motor vs. the original 52 is the motor draws less voltage to run and the 257 bulb requires a lot of current to make the flasher in the bulb work. So Lionel put the next available flasher bulb--6 volts--- as a replacement. It works, but flickers and blinks rapidly and is annoying. As a side note, I have a 257 bulb in my 8379 PRR fire car and it works great.