I remember touring the GM Fremont, Calif plant in the mid late 60s. They made the mid sized A platforms there, and it was amazing to see the various models coming down the line all mixed up...a Chevelle, then a Skylark, Cutlass or a Tempest. And as Sossol said, it was not nearly as noisy as you would have thought, but probably noisier than today...cheers
Jim