The definition of Classes 4, 2, 3, 0 don't appear to have changed since at least WW-II. I can't speak to what you'd get if the bearings were made you know where, but what has changed at least in the USA is the average quality of the assembly line output. So although you have no guarantee of an unmarked bearing being good enough to be a Class 3, most apparently are. The way that the assembly lines use to work (and probably still do) was that any components that were sold in two or more qualities were tested until enough of the highest quality that orders existed for were made. Then the same for the second quality. And so on. So given that Timken claims not to sell any Class 4, the unmarked Class 2's are probably good enough to be marked as Class 3 but aren't marked as such.