For the 2008 GMC Sierra 2500HD, the low-beam headlight uses an H11 bulb, while the high beam uses a 9005. The supplied fitment data does not identify separate bulb sizes for projector and non-projector headlight assemblies, so confirm the housing style before ordering if your truck has replacement or modified headlights.
Other useful exterior lighting sizes include 5202 LED for the fog lights and H11 LED for the daytime running lights. The front turn signal and parking light use 4157NA, while the front side marker uses 194NA.
- Rear turn signal: 3047
- Brake and tail light: 3047R
- Reverse light: 3047
- Center stop light: 921
- License plate light: 168
For interior lighting, the dome and map lights use 212-2, and the listed trunk light uses 912. Match the bulb function and socket before installation, especially where LED-specific fitment is listed.