That would be the 4L80E/4L85E automatic transmission. The E stands for ELECTRONIC.
The 2008 GMC Sierra-2500HD has a 6-speed automatic.
The 2008 GMC Sierra-2500HD has a V8 engine.
The 2008 GMC Sierra-2500HD has 16 valves.
The 2008 GMC Sierra-2500HD has overhead valves (OHV).
The 2008 GMC Sierra-2500HD is a gas-powered vehicle.
The 2008 GMC Sierra-2500HD runs on regular unleaded.
The 2008 GMC Sierra-2500HD is 18 ft. 8.7 in. (224.7 in.) long.
The 2008 GMC Sierra-2500HD's turning circle is 45.3 ft..
The height of the 2008 GMC Sierra-2500HD is 6 ft. 4.4 in. (76.4 in.).
The 2013 GMC Sierra-2500HD has a 6-speed automatic.
The 2001 GMC Sierra-2500HD has a 5-speed manual.
The 2004 GMC Sierra-2500HD has a 5-speed manual.