welcome to the board Chief. Check the tires, you want E rated with the highest weight rating that will fit on the rims. The more plys to the sidewall = less sway. If the shocks are old swap em out for something newer and heavy duty. The rigs handle like an engine with a 2/3 full load of water.
I just retired in Dec from Santa Cruz County Fire.
2011 F350 6.7L Diesel 4x4 CrewCab longbed Dually, 2019 Lance 1062, Torqlift Talons, Fast Guns, upper and lower Stable Loads, Super Hitch, 48" Super Truss, Airlift loadlifter 5000 extreme airbags