what is the difference between a chevy avalanche z66 and z71?
The Chevy Avalanche Z66 Was an Obscure Premium On-Road Truck. Every truck enthusiast knows what Z71 means. Z71 is code for the rugged off-road style and capability of GM trucks. ... It was the Z66 package, and it turned the Avalanche into a "premium on-road truck," according to Chevy.