Just recently found this about a day or so ago when browsing some news for UP 4014, Although as in the video it took them some time before the whistle sound was refined. But once it is, that sound, its just beautiful. One step closer for this iconic steam locomotive to make its re-debut on the mainlines.
For me personally interesting and exciting to see this good old hauler come back to life, well worth the wait .Kudos to the UP steam shops for their dedicated work as well.