Depending on the manufacturer, a model year, say a 2021 as an example may have been built as early as late fall of 2019. My brother has a 2017 Flagstaff with a build date of Dec 2015, which he bought in 2016.
Want to make it more confusing? They sometimes will make major changes any time they care to so a 2020 might have 2 or 3 versions, move the dinette to the other side, eliminate a window, change the bathroom layout, etc. That is why they all have the disclaimer that says something to the effect of "During the model year, it may be necessary to make revisions and we reserve the right to make changes without notice, including prices, colors, materials, equipment and specifications as well as the addition of new models and the discontinuance of models."
The entire Industry is mostly a load of shysters, honest folks who are competent are few and far between no matter if it's a manufacturers sales or warranty rep, or a dealer. When you find one you can trust stick with them if you can.
