Opinions needed

My car has developed a new problem, just wanted to see what everyone thought.
Really bad vibration, or shutter from about 22-30 mph. does this in any gear, but only from 20-30mph. My first thought was u-joints or maybe driveshaft related but the speed of the drivshaft changes with each gear change so Im not sure. I wouldnt think it was a tire out of balance because of the low speed involved. Anyone have any thoughts?

Also if you free-rev the motor I get no vibration, I only get vibration during acceleration through the mph range, but not decelerating through that range.