My experience with truck tractors is that every once in awhile the shift lever would break. The business end of the shift lever has a hole through it that it pivots on and then the last couple of inches is a flat finger that sits in a square pocket that are the shift rails. The shift finger slides the chosen rail/gear as you move the shifter up top.
The ones I've repaired have broken at the hole that the shifter pivots on. The repair was to unbolt the shift tower at the transmission top cover, take the broken piece out that is sitting in the square pocket, take out the pivot pin, install new shifter installing pivot pin through the hole in new shift lever, bolt the shift tower back on to the top cover. This could all be done up top by usually just taking off the shifter boot and maybe a few pieces of sheet metal.
I may be all wrong and it might be a completely different set-up on your Jeep. If it's the way I described above, the repair is pretty simple. It just looks bad.
The part probably just failed. I've seen some ham-fisted truckers break them, especially if it was real cold.