I had a 2003 GMC 2500 with the duramax. I replaced the factory shocks within the first 10k miles with Bilstein 4600 and noticed a better ride as well as more control.
A second change that I made was to replace the rear only cab mounts as they were redesigned somewhere around 2006? These mounts will fit your 2002 and are worth the cost and effort. It took me less than an hour and were relatively inexpensive. Definitely worth doing. Good luck!