Loud THUNK sound that is somewhat concerning

[J.R.]

Differential noise maybe. That's where I'd start. Hopefully she doesn't start to whine too...

My guess is rear dif as well. Tends to happen when you 'overload' on demand AWD systems with WOT.

I wouldn't worry too much OP if it isn't still happening under normal conditions and/or making other 'bad' noises now.

 

[Fishah]

You mean like I said in #4 above?

Yep.