Assuming that you desire a 6.5' Truck Bed for a 2011 GMC 3500HD, then you might need to look at other truck models. Other alternatives such as GMC Sierra 1500 or some versions of the GMC Sierra 2500HD have 6.5-foot beds. These trucks offer an equilibrium between cargo and easier maneuverability. They are more compatible with daily driving but also have good towing capacity. The selection of the appropriate model will depend on your preference of either heavy-duty performance or convenience and flexibility.