I would stop using ANY Vehicle with a Possible transmission issue.
Just a heads up -- I once owned a Trans Repair Shop !
There are many You Tube Videos on your Transmission you could
watch,to get an idea of the possible issues,IF the trans is involved.
I will say & others could tell you something different,But guessing between
U-Joints or Differential & not actually getting under the truck & do some looking,
listening or testing,is not going to give you an answer,nor is having us guess
on the internet.
I have a 2014 Frontier.
Almost all issues with that vehicle are well known & on the internet & fairly easy
to figure out & resolve,unless your going to pay a shop to guess & who knows what else.
Unless you or previous owner has never changed the fluid,then there should be no reason for
a trans issue.
You can crawl under the vehicle & remove the drain plug & or trans pan without even raising the vehicle,
I have done mine,& the is no filter,just need a new gasket.
Sounds trans related,as u-joints pop or snap or whatever & you would know if a rear axle bearing
was going or diff failed.
I believe on the yours if you have a Dana Axle verse a Nissan,that they had bearing issues.
May have to remove the valve body & clean it if the solenoids are not dirty & working properly.
Not changing the fluid every couple years causes issues.
Don't waste money at a dealer for Matic S Fluid
Go to Auto Zone for Castrol Full-Synthetic Multi Vehicle part # 06519.
That is the only LV Fluid I know of that is the same as the dealer fluid.