Thud/Slight Grinding Noise

I have noticed probably within the last 2 weeks, I had been getting this thudding/grinding noise that I can hear/feel when driving....usually I will start driving at it will start around 20mph and especially if I am going up an incline, the sound is much more noticeable. Once I hit 40mph, the noise continues and once I hit 45mph-50mph...It either quiets down or is masked by tires, etc. Trying to figure out what I could possibly getting into. I know that when my girls Ring & Pinion went bad, her jeep would vibrate really bad at any speed about 30mph, so I am thinking wheel bearings possibly? I can't tell if its coming from the rear or the front....I can put my feet directly on the floorbard and feel the vibration/thudding/grinding. My front driveshaft is NOT connected at the moment to rule our anything dealing with that....just trying to get an idea on what it could possibly be....
It seems to have gotten worse in the last week.

check your u joints on the front axle, the front drive shaft and rear drive shaft.. shouldnt get any movement out of them..