The '98 cases are a little bit different, the swingarm hole is larger in the '98, and the motor mount holes in the front and bottom are smaller, and i think that the crankcase area is smaller so you cant put a newer cylinder on it(i think) been so long since i had it apart, but i think that is what it was, i know that the cylinder and head are different for sure, side covers are the same, and clutch stuff is too. Trans will swap out with newer stuff.