Chevrolet Silverado 2500 2020–2024 — technical service bulletin
Bulletin 21-NA-120 · NHTSA communication 10243980 · issued Sep 19, 2023
Technical service bulletin
communication type
Power Train
component
2020–2024
model years
20
vehicle entries
Official summary
This service bulletin provides a Diagnostic Tip for Noise, Vibration, and/or Harshness Issues/Clunk Noise Heard During Coast Down Event after the transfer case was removed from the transmission and reinstalled during a recent repair.
Vehicles covered
- 2020 Chevrolet Silverado 2500
- 2021 Chevrolet Silverado 2500
- 2022 Chevrolet Silverado 2500
- 2023 Chevrolet Silverado 2500
- 2024 Chevrolet Silverado 2500
- 2020 Chevrolet Silverado 3500
- 2021 Chevrolet Silverado 3500
- 2022 Chevrolet Silverado 3500
- 2023 Chevrolet Silverado 3500
- 2024 Chevrolet Silverado 3500
- 2020 GMC Sierra 2500
- 2021 GMC Sierra 2500
- 2022 GMC Sierra 2500
- 2023 GMC Sierra 2500
- 2024 GMC Sierra 2500
- 2020 GMC Sierra 3500
- 2021 GMC Sierra 3500
- 2022 GMC Sierra 3500
- 2023 GMC Sierra 3500
- 2024 GMC Sierra 3500
What a TSB means. Technical service bulletins are repair guidance manufacturers send to dealers — they are not recalls, and repairs are not automatically free (warranty extensions are an exception worth checking). The full document is available via NHTSA’s vehicle lookup.