General Motors will offer an optional six-speed Allison automatic transmission in its 2006
Chevrolet and GMC HD 2500 and 3500 pickup trucks, equipped with the 8.1-liter Vortec gas
and 6.6-liter Duramax diesel engines.
The new transmission will be similar in construction
to the existing five-speed Allison, but it will incorporate a number of new operational
features and improvements. Pricing has not been announced yet.