No, it's not ng, but that entire line, including the tunnel, is most interesting. Try to imagine ATSF 2-10-2s & 4-8-4s pounding up throught that Canyon as they did into the 50's. When I worked at GCR, one of the engineers took me out there when we both had a day off together. It's well-worth the little effort to get out there.
Look back at the first photo of 4960...there's something changed here. I had been told that the shop had modified the exhaust & now she & sister 29 both have Lempor (sp?) exhausts, which are designed to lower back pressure & contribute to greater efficiency. 29's stack is different now, but not looking like 4960, it has a much greater flare from bottom to top.