General Motors will pair a new 8-speed transmission with its 6.2L V-8 engine offered on 2015 Chevrolet Silverado 1500, GMC Sierra 1500, GMC Yukon Denali, and Yukon XL Denali models.
The Hydra-Matic 8L90 automatic transmission replaces the Hydra-Matic 6L80 6-speed automatic transmission. The 7.0 overall gear ratio spread is wider than the 6-speed and provides a numerically higher first-gear ratio to help drivers pulling a heavy load during trailering. The 8L90 also enables numerically lower rear-axle ratios that reduce engine rpm on the highway.
The 6.2L EcoTec3 V-8 provides 420 hp and 460 lb.-ft. of torque. General Motors has adopted the SAE J2807 towing standard for its 2015-MY trucks. Versions of the trucks with the V-8 and Max Trailering Package maintain their tow ratings of 12,000 pounds.