6-speed Allison transmission

GM decided to offer this versatile 6-speed automatic transmission with the Duramax engine. Supplied by legendary transmission builder Allison, this stout piece communicates electronically with the engine and can operate over a wide range of modes:

• Range selection mode
• Grade braking
• Cruise grade braking
• Shift stabilization
• Tow/Haul mode
• Low traction mode
• Heater performance mode
• Adaptive shift control

Read more: 2007 Chevrolet Silverado 2500HD Duramax test drive and review