not 70s but my Mercedes 300TD from 1985 made extensive use of vacuum hoses to power lock doors, run pumps and even to turn off the engine (it's diesel so no spa

not 70s but my Mercedes 300TD from 1985 made extensive use of vacuum hoses to power lock doors, run pumps and even to turn off the engine (it's diesel so no spark plugs.) I think it was built that way because electronics were more expensive? the engine was a marvel of engineering. I got it to 400K+ miles (odometer eventually broke), and I could drive just fine even after my alternator broke and I had no electrical power whatsoever. I also could (and did) do extensive maintenance myself because there were no computers to fiddle with and everything was modular.