The grooves are on the spindle proper. I do not know if I have the vocabulary to explain my dilema, but I will try. There are two races(?) that "hold" the ball bearings in place. One is at back of the hub and the other is at the castle nut. They are NOT the races that are inside of the hub. My guess is they started turning and wore the grooves in the spindle. I got the disc brake conversion kit from CPP and it has a bearing adapter at the rear and a roller bearing at the castle nut side. I wanted to make sure those items would fit correctly. If you need any more information, please ask! thanks again
