I'm going to install a WR stator on my YZ426. I've read that the WR426 to YZ 426 is a direct swap. I also read that the 98 and 99 WR 400 have a lower output stator (wattage) than the 2000 model. The 2000 WR 400 has the same part number as the 2001 WR426 stator: 5NG-85560-01-00 My question is the flywheel - which one do I need to get and why do they have different part numbers? 2000 WR 400 flywheel: 5BF-85550-01-00 (also says 5GS5) 2001 WR 426 flywheel: 5NG-85550-01-00 (also says 5NG1) Does one change the output? Stator cover is the same part number, so I don't think they have different dimensions, at least on the outside. Are the crankshafts different? Different taper perhaps? If the two flywheels will work on the same stator part number, maybe that is the different.