Even after that, original route remained in use in to serve a few ranchers along the line until the war came, and the rails were needed for the war effort.
I read a great article years ago about the removal of that track. A contractor did it with a couple of moguls bought from somewhere, and to begin the work there was a reverse-golden-spike ceremony at the original golden spike location. The two engines touched pilot to pilot and everything. Apparently the rails went to be used for trackage inside a navy base on the west coast.
It is doubtful that this route was ever sullied by the turn of diesel wheels.
Incidentally, I have five of those ten-wheelers in different road names and a couple undecorated. I've had them all a very long time and they're flawless in operation. I think only one remains with factory installed DCC/sound and the rest have Soundtraxx Tsunami2 decoders. When you finally get your engine the way you want it you will love it.
Bachmann is an importer and vendor, not a custom service center. They will not do an install. Their service center, while very good for what they do, is really for minor repairs at most, and occasional warranty replacements.
You would appear to be best served by having a professional DCC/sound installation done by a professional tech. There are dozens of them on the Internet. Google is your friend. I've never tried to do an install myself and I am a Model Railroader with 60 years experience. It won't be cheap, but it will be right.
I have a friend who has done all of my DCC/sound for years, maybe 25 engines now. You can count on around $150-200 for the parts and around $100 for the labor, maybe more, I'm not certain because my friend gives me a much better rate, although I do pay him. I did say that this was expensive to have it done by a pro. But it will come back done right.
You can certainly try to do it yourself. There are many videos on the Soundtraxx website about installation of sound, operation, and scores of other related subjects. The staff guy who did those videos is a personal acquaintance who has done a very extremely good job with those videos explaining everything. And the best thing is, you can call him on the phone if you don't understand something or have questions. He's a very good guy and very accessible. There's lots of help out there, you just haven't been looking in the right places.
I'm sorry about the frustrations you have experienced. Model Railroading is not a plug and play hobby, but rather a sequential multi faceted learning experience that goes on for a lifetime. Sometimes it isn't for everyone, I know a guy who didn't have the dexterity and temperament for it, and finally gave it up.
I started Model Railroading in 1961 and I still have to figure out things at times. But I did enjoy building my layout and I still enjoy operations on it.
I just looked at the N scale light 4-8-2 whistles on the Soundtraxx website. The Econami decoder has 15 whistles, some really great ones, but I do see an Illinois central steamboat whistle. It may not be the very whistle that was on the Frisco 1522, but a steamboat whistle is a steamboat Whistle, they really didn't differ that much from each other. In my experience, the tone and pitch of real steam whistles varied quite a bit with atmospheric conditions and prevailing winds.
It is true that the Frisco was known for steamboat whistles on its engines. But it did not have steamboat whistles on every engine at any given time.
Railroads changed whistles on their steam engines during regular shoppings like we change socks every day. If you look at photos of engines at different periods in their lives and look closely at the Whistle, you'll see more often than not a different one every time. Hot steam is very abrasive and would create heavy wear on the cell apertures, compromising the tuning and overall sound, and ending up with a terrible raucous tone. The whistles themselves had to be shopped just like any other moving part, but the engine needed to get back in service as soon as possible, so a repaired and ready Whistle would go on the engine while the worn one went to the backshop for repair.
With all of that in mind, I wouldn't be surprised if the 1501 one carried a six chime at some point in its life. Personally, I love that Frisco Six chime on the Soundtraxx decoders that I have. It's a pretty standard Nathan six chime but it's also very correct for Southern Pacific and Missouri Pacific engines. That whistle and the Rio grande 486 5-chime are very typical of southwestern railroads and are standard on my engines.
I have a photo of a Gulf Coast Lines 10 wheeler with a Vanderbilt tender. The engine is a dead ringer for the Bachmann 63 inch driver 10 wheeler currently not in production. The Vanderbilt tender is almost just like the medium oil tender Bachmann sold years ago, with a couple of handrail modifications. Neither is offered anymore, but fortunately I have both. So, Gulf Coast Lines 10 wheeler number 33 will soon be on the rails at my house.