The Avalanche comes in two weight ranges, called 1500 and 2500. The 2500 comes in 4WD only. As with other Chevy trucks, Avalanche is offered in standard LS and more upmarket LT trim. It is powered by a 325 hp 8.1-liter V-8 that is controlled by a four-speed automatic transmission. The unique feature of the Avalanche is the clever Midgate that allows the rear passenger seats to be converted into additional flatbed space.For 2006, the Chevrolet Avalanche sees minimal changes. A tire pressure monitor now comes standard.