The 2011 GMC 3500HD has no known factory option 6.5' Truck Bed for a 2011 GMC 3500HD 2011 model was actually designed to accommodate a heavy payload and towing capacity with an 8-foot long bed. This design provides enhanced weight balance and enhanced stability, particularly in commercial applications. Most light-duty trucks have shorter bed lengths; the 3500HD is more functional than compact, with the 6.5-foot bed length not fitting its standard setups and intended usage.