For the 2005 GMC Sierra 2500HD, the low-beam headlights use 9006 bulbs, while the high-beam headlights use 9005 bulbs. The supplied fitment data does not identify a projector or non-projector headlight distinction, so verify the original bulb before ordering if the truck has replacement or modified headlamp assemblies.
The fog lights use 9145 LED bulbs. Front turn signals and parking lights use 4157NA, while the daytime running lights use 4114. At the rear, the reverse lights use 3157, the brake and tail lights use 3157R, and the rear turn signals use 3157A. The center stop light uses 921.
For exterior utility lighting, the license plate bulbs are 194, and both front and rear side markers use 194NA. Interior fitment includes a 194 glove-box bulb, 578 map-light bulb, and 912 trunk-light bulb. Courtesy lighting may use either 194 or 2721, and the dome light may use either 578 or 211-2; compare these bulbs with the originals before replacement.