MC, I've owned my K0 since new and the original spacers looked like they were made from standard washers with a flat spot ground on them and with the inherent weakness of the triple tree, I thought the washers were too thin. After all, both sides of the tree broke. The lower tree, made from steel, iron or some such, does the real holding in the vertical direction. I figured the upper just needed to locate things and be snug. Seems to work. Don't want to buy another upper - they're getting pricey.