* 6L90 6-speed automatic transmission: This was the standard transmission for most models, including those with the 6.0L V8 and 6.6L Duramax diesel engine.
* Allison 1000 6-speed automatic transmission: This was available as an option on the Duramax-powered models and was known for its robust construction and heavy-duty capabilities.
To know the specific transmission in your 2012 Silverado 2500HD, you can check the VIN (Vehicle Identification Number) or the owner's manual. You can also consult a reliable online source like a vehicle history report website.
