The car I am working on was originally a 23 spline 833 4 speed transmission. I have read many times on here that the 18 spline unit is much stronger. Could someone clarify what specific areas are beefed up?

Also this is probably a dumb question, but isn't more splines on an axle stonger? Why is this different for the trans shaft, I.E 18 splines are stronger than 23?

Thank you for any input!