The 2013 GMC Sierra uses a six‑speed automatic transmission in most configurations. The exact unit depends on the model and engine: light‑duty Sierra 1500s mostly use GM’s Hydra‑Matic six‑speed automatic, while heavy‑duty Sierra 2500/3500s use an Allison six‑speed automatic. There was no manual transmission option offered in 2013.
Light‑Duty Sierra 1500: transmission overview
The 1500 lineup typically paired its available engines with a GM six‑speed automatic transmission from the Hydra‑Matic family. The following are the common engine–transmission pairings for 2013 1500 pickups.
- 4.3L V6 — Hydra‑Matic 6L80/6L50 six‑speed automatic
- 5.3L V8 — Hydra‑Matic 6L80 six‑speed automatic
- 6.2L V8 — Hydra‑Matic 6L80 six‑speed automatic
In summary, the light‑duty Sierra 1500s generally use a six‑speed automatic transmission regardless of the engine option in 2013.
Heavy‑Duty Sierra 2500/3500: transmission overview
The heavy‑duty Sierra 2500HD and 3500HD employ a different automatic transmission. These models are paired with an Allison six‑speed automatic transmission, used with both the Duramax diesel and larger gasoline V8 options.
- Duramax 6.6L diesel — Allison 1000 six‑speed automatic
- 6.0L V8 gasoline — Allison 1000 six‑speed automatic
Conclusion: The heavy‑duty Sierra models (2500/3500) use the Allison 1000 six‑speed automatic, distinguishing them from the light‑duty 1500’s Hydra‑Matic transmissions.
Notes on 4x4 and configurations
Whether two‑wheel drive or four‑wheel drive, the main transmission type remains the same within a given model line; four‑by‑four configurations may involve a different transfer case, but not a different primary transmission family.
Summary
For the 2013 GMC Sierra, the transmission answer depends on the model. Light‑duty Sierra 1500 trucks use a six‑speed automatic from the Hydra‑Matic family (6L80/6L50), while heavy‑duty Sierra 2500HD/3500HD trucks use an Allison 1000 six‑speed automatic. No manual transmission option was offered in 2013. To confirm the exact transmission on a specific vehicle, check the VIN or factory specifications.