Acutally, the bulb is burnt out if it doesn't light anymore. Pop the clock out of the dash and you'll see the bulb holder on the back of the clock, it's a black twist base, down in a round recessed hole. Get something like a flat screwdriver or if you can, carefully remove the white backing on the clock to make twisting the holder out easier. I'm not sure what the # is for the bulb, but some say you have to buy the base and bulb together, others say they've just bought the bulb w/o the base. Your local Ford dealer can get the bulb, but they probably want a forune for it, (what else is new... )