For the 2008 GMC Sierra 1500, the low-beam headlight uses an H11 bulb, while the high beam uses a 9005 bulb. The supplied fitment data does not list a headlight-type variation, so these are the listed applications for this model year.
The fog lights use 5202 LED bulbs, and the daytime running lights use H11 LED bulbs. For front signaling and parking functions, the listed bulb is 4157NA; the front side marker uses 194NA.
At the rear, the turn signal uses 3047, while the brake and tail lights use 3047R. The center stop light uses a 921 bulb. Other listed applications include 168 for the license plate, 212-2 for the dome and map lights, and 912 for the trunk light. Confirm the existing bulb and socket before ordering, especially when selecting LED replacements.