Major manufacturer lines get a new name with major emissions changes, but the PIN (Product Identification Number) is the key for parts. The 3 I worked for engineering wise always tracked changes affecting service by S/N or PIN. At old AGCO we went by model and S/N. Cat changed to a 17 character PIN that has all kinds of info but not year of manufacture. It was not important to us. People on assembly line began 2001 finishing up the machine on which they were assembling before Christmas 2000. The big change may come in May, or August, or whenever we had met all he goals for having a new model ready to introduce. And the first 320 excavator of a series built in Japan was probably produced a year or two before the same model produced in France or America. So at Cat it was whether you had a D11R or D11T that was important, along with hours and condition, not year built. I’ve only found year built on my Kubota tractors when the dealers have added on paperwork at trade in day. Like I bought my L6060 in October 2016 but just saw year built 2015 on the paperwork when I traded. It didn’t make a difference to me when I bought it - newly assembled out of shipping rack.