Here are some of the photos of the pile of driving wheel centers at the Longleaf mill. The ones with the slot around the wheel are from an 1883 Baldwin 2-6-0, and the ones with a solid circumference are from a 1919 Baldwin 2-6-2.
If you study the first photo, you can see that the slots are not exactly in the same spot in the wheel nor are the spokes braces across the slot in the same place nor are they the same size, meaning that a different pattern was used for each wheel center. At least on #20, in Linn's picture, it seems like the slots are all the same and the cross bracing the same also.