After saying goodbye to our 5er (earlier post) I will be checking the hangers where the leaf springs are attached and checking for broken welds as well as taking a peak under the corrugated plastic to be sure any cross supports are not showing any damage. This and check every corner of every cabinet for previous water damage. As Likes to Tow mentioned these are constantly vibrating themselves every time you hit the road, look for separation where the shower mounts to the walls and where ever cabinets meet the walls, if there's any separation it could be a future problem.
That and check the sealed corners for failure but really look at the axles and leaf springs.
