When you are on the gas; you have tension on your joints and bearings on your drive train. When you release the gas the tension is off and if you have anything lose; it will vibrate/slop around.
Check the drive shafts u-joints and also see if the CV is sloppy. Grease them if they are greasable.
Check your pinions also... the bearings might be toast. Open up your diffs (that means changing the fluid in both diffs) and see if there are any metal shavings in the oil. Stick a magnet in the oil if you're not sure...see if your oil looks like metallic paint. usually the bigger pieces are in the "groove/divit" inside the diffs.
If your Lazy (like you said)... don't ask questions and just go see Dave and Eric at Brokenaxles
...
If you decide to do the work; 'et us know what you find.
Good luck
Dom