rear differential question

I need some help from the raptor gurus. I recently started having a loud grinding issue, took it to a shop and was told it was the transfer case. Got another installed and the grinding is still there, waste of $700+. Now I'm being told it's the rear diff. It sounds like it come from the back sometimes in the front, mind you I have a 2010 5.4L. since im told it's the rear diff, I'm looking into a kit, replacing the gears etc. But not upgrading gear ratio. Keeping it the same but which would be best durability wise that can handle some abuse over stock?

What in particular are you asking about handling abuse? Bearings? Ring and pinion? The differential?

What kit would I need for my 2010 to replace everything in the differential.

Shotgun approach is not a good way to address whats going on. The first repair is a good example of that. Find a first rate mechanic and trust his judgement.