The 2008 Chevrolet and GMC T-Series delivers more power and more torque from the 6H engine's base rating, along with new six-speed Allison transmissions, a vertical Diesel Particulate Filter (DPF) option and new features designed to improve driver convenience and enjoyment. For T6500 and T7500 customers, the standard transmission is an Allison 2500 Series six-speed with a GCWR rating of 33,000 lb. Also available is the Allison 2200 Series close-ratio six-speed transmission with integral park pawl and GVWR/GCWR rating of 26,000 lb., and a 2550 Series wide-ratio six-speed transmission with integral park pawl and a GVWR/GCWR of 30,000 lb.
All three receive the Allison Edge Standard Transmission Coverage for up to four years/ unlimited mileage on HS Series vocational models. Factory-fill TranSynd transmission fluid is standard, and required by Allison to allow the longer service coverage. TranSynd can also extend Allison transmission oil drain intervals up to 400 percent, further reducing vehicle downtime.
Other Allison vocational transmissions available on the T-Series include the Allison 3000 RDS close-ratio six-speed automatic transmission. It's standard on T8500 models and is available on T7500 models. Available on all T7500 and T8500 models are Allison 3500 RDS, 3000 EVS and 3500 EVS transmissions - offered in five- and six-speed versions. All of these transmissions include improved controls for smoother shifts.
T-Series customers may also equip their vehicles with an Eaton-Fuller manual transmission available in six-, nine- or 10-speed (8+2) configurations.