It's really too bad you can't drive it. It would be nice to put some miles on it, to prove out the structural integrity. When you talk about the slides needing adjustment, that seems like the upper frame may be tweaked. Freightliner would only be able to check the frame underneath, and would not have any way to prove the house frame is OK. With a hard impact, the whole box could have tweaked forward on the frame. It would be good if you could prove the vertical stringers are all still vertical and attached to the floor. Might be worth checking to see if the hole for the slide is sill square.