I would start looking at the pro 4x model it comes with a
dana 44 I believe *don't quote me I would have to go look at
mine out in the drive way , it comes with a switchable on the
fly posi-trac that I keep locked in except for when it is
raining. *I believe it to give my truck more even tire wear and
the passengers side from spinning when making every right.
Traction control and down hill towing assistance is more
than likely the only thing you would have to look into, a
junkyard frontier pro4x should not be hard to find. Now what
year they started putting the posi in I have no idea.
https://ahparts.com/used-auto-parts/nissan/frontier/19-
066-3
Rear diff
https://ahparts.com/search/2016/Nissan/FRONTIER/dif/43
5
If it were me I would start with looking at what differences
there are with the wiring of the traction control and down hill
assistance other than that the platform has been the same
from day 1.