Originally Posted by Oldpeddaller

As I remember it, it's an era thing. The stems up to about the early 1970's all used expander nuts but then there was a migration to the wedge arrangement that is simpler to make, (usually) releases more cleanly, tightens firmer = but is a REAL PITA if it gets well & truly seized! YMMV, I could be wrong but that's the way I remember it now. please correct me if I got it wrong.