I had a 1955 210 back in the day. Based on the serial numbers it was the 14th car built by GM. According to a former engineer who worked for GM back then, the first car off the line was hand built and donated to the president of GM. It would be pretty much junk and he donated it to the Smithsonian Museum. The first 20+ cars are hand built because nothing fit and they had to "tweek" the parts to get a proper fit. By the time the 10/11th was built they were fitting very well. I remember my 55 never had a rattle and I figured it was because of the hand built deal.
Good luck with your 55.
