I have fitted a set of Purple Line Ego units to my 20.63.1 OB. Easy to fit as the chassis already had the mounting points for the Reich movers ex-factory. Need to fit a dual battery as the drain from both units was a bit beyond what I was comfortable with from a dual unit. I do have the full step by step photos from when I fitted the unit that I am happy to post if anyone is interested. I use the units to get my van up into a tight spot at home - not necessarily while we are on the road although they are great for minor repositioning. With the OB units the deeper tread of the tyres make turns a little tricky as the knurled rollers "flick" off the tread reducing the grip on the wheel. Standard tyres with minimal tread depth would be a better match for these units. The other issue is that when you have a bit of weight on the ball, and you are on a soft surface - the jockey wheel wont easily spin to the correct orientation to commence the turn - so you can have a wheel at right angles to your turn in soft ground resulting in a bent jockey wheel shaft - most embarrassing. The trick is - full the rear water tank, lower the wheel right down to reduce leverage, and only use on hard surfaces. Having said that - with 200kgs+ on the ball, even on hard surfaces, you will struggle to get the jockey wheel to do what you want. Note that my jockey wheel is centre mounted so being set back 300mm or so from a front mount. I suspect that being closer to the fulcrum (wheels) there is more force on the jockey wheel.