For the 2008 Ford Expedition, both the low-beam and high-beam headlights use an H13 bulb. The supplied fitment data does not identify a projector or non-projector headlight variation, so verify the existing bulb before ordering if your vehicle has been modified.
Other useful exterior bulb sizes include 3157A for the front turn signals and parking lights, 4157R for the brake and tail lights, and 4157 for the rear turn signals. The reverse lights use 921 bulbs. Front side markers take 194NA, while rear side markers use 4157NA.
For lighting around the vehicle, the license plate lamps may use 168 or 917. Center stop, courtesy, and map lights are listed with 2825 or 98 options. The dome and trunk lights use 578, while the glove box is listed with 194 or 7441.