I thought this would be worth sharing. For the suspension of an RC model I'm working on (yes, I will keep my promise @DugaldIC), I want to have a telescopic transmission shaft that can take quite some vertical travel while spanning a constant distance of 6L, the length of a non-telescopic arrangement with two u-joint. I know about Sheepo's design, but that one can only take little vertical travel before the slider axles collide with the u-joints. So I've been playing with this a little and found an arrangement that works very well. It can take quite some torque actually, even though I'm not planning to use it for transferring motorized drive. This will only connect the wheels to a fake engine.