This is misleading, and I'll address the flywheels in a minute. If you're running automatic, you want the flexplate, and NO flywheel. I think wantacuda68 is saying get the balanced flexplate for the 5.9. I doubt Rockauto will have that, I thought that they focused on OEM parts, which may nor work with your torque converter. Perhaps another member can chime in on that.
Yes, the flywheels changed (the tone ring mounting changed), but I'm not sure when and it doesn't matter. Our cars do NOT use the truck wheels in any shape or form.