Lindsay, how do you know it was the 58th built?
I had a 55 back in 1963 and according to a GM engineer friend of mine, back then the first few cars they built in every model year, were just junk. They had to mock up the first 8 or 10 cars before everything would fit. After car number 10 or so they were put together very well with much more attention to detail (every bolt tight). This went on until GM was satisfied with the quality, probably 15th car or so but, they still continued to hand build; I'm not sure for how long.
Car number one was given to the GM president who gave it to the Smithsonian.
My 55 according to the VIN number was the 18th built and I could drive any bumpy road with no rattles. It was really tight.
