For the 2020 GMC Sierra 2500HD, the listed headlight fitment uses D5S bulbs for both the low beam and high beam. This means the same D5S size is specified for both headlight functions. Confirm the existing headlamp housing and bulb markings before ordering, especially if the truck has replacement or non-original lighting components.
Other useful lighting sizes include 5202 LED for the fog lights and 7443 for the front turn signals, parking lights, brake lights, tail lights, and rear turn signals. The center stop light and trunk light use 921 bulbs. For exterior auxiliary lighting, the license plate lights use 2825, while the rear side markers use 194.
- Low beam: D5S
- High beam: D5S
- Fog light: 5202 LED
- Front and rear signal, brake, tail, and parking functions: 7443