Re: dual gauge coupling

Hi Gary,
You are speaking of the knuckle. I am not sure about your photo but most likely one of the extra coupler is probably missing one of the pins and knuckle. They were easily removed by lifting the pin out and pulling on them (have your feet clear or you'll lose some toes). When a broken knuckle was found in a outbound train, the crew would grab the nearest that was not presently in use. If there were three coulplers on the loco. only two would be needed unless the loco happened to get turned. In three rail territory, the 3' was always on one side except on one leg of a wye where a"draw" moved it back to the same side with 4 rails for a few car lengths.
There is no record of the often changes of extra drawbars added and removed from various engines over the years. The best is shown in new book on Leta Pass, showing D&RGW switcher with piston activated diagional coupler shift.
There were no SG cars at Durango during the short time #50 switched or turned the Silverton train there. Hope that helps.