SteamDB is an Open-source 3rd party website that takes the data provided by Valve and steam, Game IDs prices, Concurrent players, etc, and displays it in a user friendly interface through a website --- Post updated --- So yes you can trust it.
copy steam://open/console/ and paste it in the address bar on your web browser. Allow it to open the link in Steam.
it won't remove previous data, it saves in the [location steam's installed in]/Steam/steamapps/content/284160/ folder.
I think I picked the wrong number because after downloading it just downloaded 0.31.3 --- Post updated --- Do I include the "m:" in the number?
I tried downloading a version of 0.19 but I could have just did it wrong so I will test the ID from august 6th.
only real lost version of beamng is the cryengine3d one, all other ones are either out there or never released publicly, you can almost get all off them from steam
however, some aren't available online and are stuck on some old dusty hard drive from 10 years ago. that's when the "lost versions" parts kick in because they aren't publicly available but were publicly released at some point in the past.