Ya the droopy body-
the '98 F250 was a transitional truck as mentioned, F150 body, though if I understand correctly it was sold for couple of years (with new body, lighter components) along with the new F250-SD in commercial/fleet truck lines.
98 is when I decided going in the direction of a TC- I was dreading that new SD trucks would have the droopy body. Fortunately not, though not the OBS which imo last good looking truck.
As noted Hellwig does offer a S/B, Both H/J and T/L list tiedowns (H/J thouhg shows the front body button not ear mounts?). Air lift and firestone list air bags, (though 2/3000lbs assist).
Sway bar not required but most will see improved on road handling, especially with a tall load. I don't know the weight of the SixPac hardside but that would be 1st consideration. S/B would minimize sway if noted but not compensate if over capacity.
As far as the H/J bumper bracket a brace tying to frame can easily be fabbed to help with bumper twist, or possibly the one they sell might be modified to work.
