There is a thumping noise when acclerating?

My vehicle listed above makes a thumping noise when I accelerate. Sounds like a flat tire but it's not. I added oil to the differential, and it still does it. I checked the u joints but I'm not sure how they are supposed to be as far as working. Thought it might be the wheel bearings; there is a little play with the wheel in terms of spinning. Please help if possible.