Now I'm not certain that's the right one, so don't jump on it until somebody here verifies it. It's 3/4 double D on one side and 3/4 36 spline on the other. I cannot remember if that's right or not, so just use it as an example.
You are correct the manual steering box is a 36 spline 3/4 . I'm gonna do the u joint on mine I have done quite a bit of research on it. The joint that I found was similar to the one you posted.
