The early primary chain adjusters didn't have the "nylon shoe" on the adjuster pad...it just had this soft metal pad, permanently attached. The pad wore just a tiny bit(where the chain grooves started to show) and you didn't want to run your chain over tight.. The face of the adjuster was a bit narrower to fit a KR(XLCH type) tin primary cover. The clutch basket was narrower, so the shoe had to be a bit narrower too. I've found those nylon pads aren't always the best since the retainers often come loose, and the nylon shavings from the pad can clog your countershaft needle bearing oiler.