There are 2 different wheel end set ups for a 14 bolt.
The single nut which just has the nut, lock tab (square key)and a tab retaining clip.
The other has 2 nuts, one to set the bearings and the other as a lock nut with a lock ring between them.
If you have a single nut wheel end there has to have been a lock tab.
That's what keeps the nut from backing off.
Without the tab it would not take long before the nut backed off, either causing a blown wheel seal and a big goopy mess, or comes off completely and the whole shiterie departs from the rig... axle shaft and all.
Napa should have them, just tell them what wheel end you have and if the guy isn't a total dork he should be able to hook ya up with what ya need.