I have towed 350gal of water on a 5X10 trailer. 1 gal of water = 1.33333 lbs.
Plus all equipment to pressure wash... I had no troubles but I did have to flush the trany every 3 months.....just to give you an idea on the abuse these things can take for the size truck it is....my truck did come with the factory tow package...and the trany cooler.