NHTSA wanted Jeep to recall a bunch of Cherokee's older than that and update them to meet later safety standards. Had too many fires in rear-end collisions. They initially said no, we have fewer fires than similar vehicles, we far surpassed the requirements for the years they were built, and you cannot enforce safety regulations from one year on vehicle built in a prior year.
When the NHTSA threatened to get ugly about it, Chrysler said OK, how about if we inspect them, and any found deficient, we'll add a bracing structure to the back of the frame.
What are they really doing? Any Cherokee that doesn't have a receiver hitch, is getting one bolted up under it.