What type of transmission fluid does the 2006 chevy silverado use?

The 2006 Chevy Silverado uses Dexron VI transmission fluid. This is what will be in Your truck if You have always serviced it at a Chevrolet dealership. If You have taken it to a third party mechanic You may want to check with them to know what fluid they put in Your transmission. You do not want to ever mix different types of transmission fluid because it reduces the overall protection for Your gears. Also You should make sure to change Your transmission fluid every 30,000 to 50,000 miles depending on the condition. Check the fluid in Your gearbox every time that You change Your oil. This will let You be able to inspect it and make sure that it is full and free from signs of metallic debris.