I have both a 2000 WR400 and a 2002 WR426. I assumed the wheels were interchangable from one bike to the other. WRONG! The front is close and will probably work with a custom spacer on the speedo drive side, and the disc is a little different design. The rear is very different. The disc is larger in diameter on the WR426 and will not clear the caliper on the WR400. Additionally, the wheel opening of the rear swing arm is different on each bike, and the wheel spacers are also a different width. The spacing of the disc and sprocket to each other is also different. In other words, there is no way to make the wheels interchangable without machining custom components. Anybody else come across this issue?