Okay! Done Deal!
I took the hubs apart. There was old blackened grease that was runny on the outer bearings. The inners had decent grease on them still, to a certain point.
I did remove them, cleaned them out good, and regreased with lithium grease, and tested it out. Works better now! Thanks guys. I did notice the click when backing up about 6 feet.
But going forward now, when the hubs are locked in is fine. No more screaming!
The bearings all seemed fine, replaced the seals of course.
My wife....well. She likes the Xterra. And is a great driver, even babies it. She just thinks it cannot take any type of punishment, due to it being a newer truck. LOL