My Explorer has a "whirring" Noise coming from the back. That only happens at high speeds. Would that be the rear differential bearings? Not clunks. There is every once in a while a jump in the acceleration but that might just be my heavy foot lol.

 

You did the first important thing, you paid attention to a noise that your vehicle is sending to you.
It might be a good move to just remove the fill plug on the pass side of the differential and see what the lube looks like.
If you don't see any shiny metal particles you have a chance to save some $$$, and plan to have it checked out further while the cost to correct may be low.
Some folks drive around with a noise for quite a while ignoring the notice only to rant and rave about why the vehicle costs so much to maintain.
What do you think/