My respect for those who drive and/or restore older vehicles grows by the day. Granted, parts for old cars aren’t particularly easy to get, but I’m guessing that if they can’t be gotten by conventional methods, a black market-type setup will always exist as long as the knowledge of how to make the parts survives.
With the proper tools/equipment, one can build practically anything needed for the “classics”.
There are a boatload of videos on YT showing guys in Afghanistan and those places rebuild and reproduce all kinds of parts for cars and trucks. It is absolutely amazing what can be done with next to no tools.