The 6.5' Truck Bed for a 2011 GMC 3500HD (which is actually 6.6 ft) normally has a length specification of about 78–82 inches. Width measures around 71 inches, and the distance between the wheel wells is around 50 inches. This truck bed would be ideal for transporting tools, construction materials, and even general loads. In terms of capacity versus size, the 6.5 foot truck bed has a better advantage over an 8-foot truck bed. However, if you plan to buy accessories like covers and racks, knowing the precise specification helps ensure that they will fit properly.