We have several, but they don't always make it into the train. The opens tend to be the ones which need work at present. On our line at least working unfitted or semi fitted is not preferred. We did a 350ton demonstration goods a few years ago and that was only partially fitted (half a dozen vans at the front) double headed with the Ivatt and Std5. I was on the Ivatt leading, and all I will say is that the vac gauge spent a lot of the time between the summit and Alresford pointing at either 5" or 0! Never out of control, but a second's lack of concentration led to unwanted acceleration.