This GMC Sierra 2500HD delivers a Turbocharged Diesel V8 6.6L/ engine powering this Automatic transmission. TRANSMISSION, ALLISON 10-SPEED AUTOMATIC (STD), REAR AXLE, 3.42 RATIO, ONYX BLACK.*This GMC Sierra 2500HD Comes Equipped with These Options *HIGH IDLE SWITCH, ENGINE, DURAMAX 6.6L TURBO-DIESEL V8, B20-DIESEL COMPATIBLE (470 hp [350.5 kW] @ 2800 rpm, 975 lb-ft of torque [1322 Nm] @ 1600 rpm) (STD), DENALI ULTIMATE PREFERRED EQUIPMENT GROUP includes standard equipment, ALPINE UMBER, FULL GRAIN LEATHER SEAT TRIM, Wireless phone projection for Apple CarPlay and Android Auto, Wireless Charging, Wipers, front rain-sensing, Winter Grille Cover, Windows, power rear, express down, Windows, power front, drivers express up/down.