When I put over 500# in the bed the truck squats down a few inches and drives more like a boat than a truck. It has nearly new 16" Cooper load range E mud and snow tires. I think the previous owner may have hauled pretty heavy loads and may have softened the rear leafs? It will act the same when pulling my skidsteer 8500# as the trailer tongue weight gets up to around 1000#. Does anyone know of a way to stiffen the rear leafs besides airbags and an easy to install antisway bar?