As noted, the bulbs can be replaced, either using a regular bulb (Ford part # E5RY-13466-BA) or swapping in LEDs. Here are some relevant links:

https://www.ford-trucks.com/forums/5...ight-bulb.html

https://www.ford-trucks.com/forums/s...9&postcount=13

http://www.cardomain.com/ride/296394/23