No earlier versions of Trainz had a completely different Content Manager software. Apparently it was developed by a 3rd party company & N3V didn't want to keep paying for the license so that's how we ended up with the one we have now. They both of their pros & cons; but the old software was...
I don't do anything special to keep track of them. If I'm running a train, I'm the engineer... I don't know what other trains are out there. If I'm setting things, I just use the built-in tools.
Don't upload the files here without their permission.
The best course of action would be to reach out directly to them either via email (typically there is one listed in the config file) or via Direct Message here on the forums.
Landrvr1 made the single-level NICTD cars; they're quite old models, but still look good. You can get his stuff by asking politely in the appropriate thread.
I'm working on a Metra Electric route.... but it's going to take a while before phase 1 is ready for release.
Very nice! I started making a highliner for Trainz ages ago, but since I don't know how to get it from the 3D software into Trainz (fully functional, I can do static things) it's been sitting in purgatory ever since.
"Fired Up Trainz", is not Trainz Railroad Simulator". One is a group of regular folks that have made some mods for a game they like, the other is the actual game made by the developers N3V. Just because some random dudes who made a route didn't respond to you, doesn't mean the entire game or N3V...