Ok so I have a 2016 f250 with the diesel. My concern is I had my sons 65 cc and my 250 dirt bike in the box along with riding gear and gas. So at most 500lbs give or take. When I hit some bigger bumps on the road you can hear the suspense hitting the stops for that top spring on the lead pack. My concern is how bad I'm I going to sag when I tow my 9000lb toy hauler. Truck is all stock.