John, I see that three-point gauges are still listed in the store. I believe these should be used to get gauge widening on tight curves. I have two of these bought from one of your predecessors around 1980, and I was puzzled as to how they could possibly work. The outer pair of studs have their slots perfectly in line – probably milled in situ. The outer rail fits snugly in the slots as a perfectly straight line and cannot adopt a curve to match the inner rail. It has recently dawned on me that the gauges would work as intended if the outer pair of studs could rotate. On my samples they are rivetted up tight, but I managed to get them to rotate freely with penetrating oil and tightly gripping pliers. Do your stock items have rotating studs?