On my first visits to Durango in the early 60's the RGS bridge was still in place. We walked across it several times and I believe I have a photo some place showing a switch stand and the track ending just beyond that switch. The end of track was only a short distance from the bridge.
I'm a little fuzzy on details but I seem to remember some stock cars being there the first time I was there and the cars gone and the track shortened on a later visit one or two years later.
Does this help or am I adding to the confusion?
Jim