Here's a video to demonstrate. As you can see when i roll the car and the suspension is fully compressed the car bumps up and down due to the driveshafts not moving enough. The problem is still there with the shocks on.
I'm cool with gear diff on carpet, but I would like to still get things work with the ball diff so I can use it on more low-grip surfaces.
http://www.youtube.com/watch?v=gTKUorS1D8g