Steering shaft joints - Are these splines the same?

[klober23]

I have two steering shaft U joints. I believe one is off an earlier 911. The one on the left is off a 73 911, but is bad. Since I have this extra one on the lright, I wanted to know if they have the same spline pitches. I have tried the older one but it seems to only want to fit on one side. I don't want to push any harder unless the splines are correct.

Thanks in advance