[Lost in the 60's]

I HOPE that arm wasn't hanging off the end of the shaft when it was aligned or the man was blind. I can see the shims in the pic...he HAD to have seen the arm if it wasn't in place while doing that.
I bought a front disc brake conversion from cpp several years ago and sold most of the parts at swap meets, as I considered them scrap. I will never will buy anything from them again. All chinese junk.
The original nut was a tension nut with crimped head to prevent backing off. IF the threads are imperial (USA), you can get original stye replacements and not worry about them coming off again.