*   First-in-class six-speed automatic transmission with two overdrive gears
    * Engine speed reduced by 250 rpm at 60 mph
    * Enables improved fuel mileage and range
    * First-in-class tap-shift range-selection feature allows driver to easily select desired gears for greater control
    * Part of GM’s rollout of 10 six-speed automatic transmission variants by the end of the decade

PONTIAC , MICH. – The Allison 1000 transmission grows from a five-speed automatic to a first-in-class six-speed automatic for the 2006 Chevrolet Silverado HD and GMC Sierra HD trucks equipped with the Duramax 6600 6.6L V-8 diesel or Vortec 8100 8.1L V-8. Also new for 2006, the Allison 1000 six-speed features a class-first tap-shift range selection function, as well as offering enhanced fuel mileage, quietness and control. The range selection function allows the driver to easily select the desired gears to match driving conditions, such as towing a trailer on a steep grade.