Extremely bad vibration

I recently began to have a vibration that feels like it is coming from under the jeep. It started as a slight vibration that has now increased to an earthquake in the cab. I can't figure out exactly where it is coming from.

It has gotten to the point that the vibration makes the entire jeep almost seem to bounce up and down. It only happens when you accelerate and stops when you let of the gas pedal. My buddies said it is possibly the rear u-joints, but it seems a little extreme to cause such a violent vibration.

Does this sound right?

2000 XJ
6.5 inch long arm kit
33-12.50 mtr
ORO steering system
regeared to 4.11's
front and rear ARB air lockers
tom woods driveshaft

Check the rear DS. Could be the double cardon, and/or the ujoints.

Thanks for help. Is there any specific way that I can check them to see if they are worn out?

Grab the drive shaft and see if it moves radially.If it move more than a tiny bit the u-joints are probably bad.

Great, thanks. I will check it tomorrow

Remove one driveshaft at a time and go for a test drive!

I agree its probably your rear drive live. Probably u-joint(s).

probably u joints but it could be your yoke cause thats what mine was