There are no heavy duty shocks that come on these trucks from the factory. There are several different setups that come from the factory though. If you look at you shocks if the bottom part of them is orange and they have a hose and a plug near the top they are autoride. The easiest way to tell is to look in the glove box. Z55 is autoride I cant remember the other codes off top of my head. There are 3 different types of shocks that it could have. Are you looking to replace them?