A max tow 2018 will have a different leaf pack in the rear. The bumped the 2018 max tow to a 4050 lb rawr and stiffer springs which is probably the difference you are seeing.
Plus if you had a 2.7L before then the springs were even softer than a 3.5 i believe
Plus if you had a 2.7L before then the springs were even softer than a 3.5 i believe