Replacing the serpentine belt on your Avalanche is similar to any GM truck these days. Look for the grey idler pulley, hook in a 5/8 socket on a 1/2 drive breaker bar and pull. Make sure you have a good connection. The whole process takes about 5 minutes, you should have a diagram on your fan shroud to show how the belt gets routed if you forget. Chevy parts www.gmpartsclub.com You can find the serpentine belt here for all chevy trucks.