Slight Grinding noise

Ok,

I have a slight grinding noise, that sounds like it is coming from the back of my Jeep.
It starts at about 35mph and then gets a little louder as you pickup speed. When you slow down it goes away. It is a 96 Jeep Cherokee Country 4.0 Automatic, so i know i have the Dana 35 with Abs.
The Jeep is all Stock.

My two guesses are either:
1. It is one of my U-Joints on the Driveshaft.
Or
2. It has something to do with the automatic transmission.
The only other thing i think it could be is the rear-end and i hope not.

Please let me know if anybody has any idea.

Thanks,

PBen....

I have that same problem only it is coming from the front of the jeep does anyone have any idea ???