Transmission:Transmission, 10-speed automatic, electronically controlled with overdrive and tow/haul mode. Includes Cruise Grade Braking and Powertrain Grade Braking (Available on 4WD models equipped with (L84) 5.3L EcoTec3 V8 engine. Included and only available with (L87) 6.2L EcoTec3 V8 engine or (LM2) Duramax 3.0L Turbo-Diesel I6 engine.)