Pull the lever located in the middle of your tailgate out and lower the tailgate to expose the two bolts that hold the taillight housing onto the end of the truck bed.
Remove the bolts from the side of the taillight housing with a hex-head socket. Both bolts are painted black and located on each end of the housing.
Push your fingers between the housing and the truck bed on the side of the housing where you removed the bolts.
Pull out on the housing to pull the plastic tabs located on the other side of the taillight housing out of the rubber grommets in the truck bed.
Remove the top bulb from the back of the taillight housing by pulling it out of the wire socket. Place the new bulb into the wire socket and then push the bulb into the taillight housing.
Press the two tabs on the back of the taillight housing into the rubber grommets on the truck bed and then tighten the two bolts into place to secure the taillight housing.
Lift the truck bed up to lock it in place.