I used to pound my 23 spline all the time and never a hitch now 43 years later I guess it should break but it hasn't.I have had two clutches blow apart and replaced 5 over the years. If its used its at least 40years old or so and when it comes to new you get what you pay

I did have had one break on a 23 spline it was run without oil in it for years and it took a snap ring and two bearings. It would simply not come out of gear until shut off