Good catch, edited to say 7/8.

LA small block same OD as well.

I like the fraction since it's easier for me to communicate verbally.
Probably why I built a 4&1/2 square configuration too.

Can even use a broken piece of an old junk shaft for mockup, to make various tools from, or whatever since they're all the same.

I have worked with alot of folks who used FEA but have almost zero knowledge or practical application of it personally.
Good to know, anyway. Thanks for chiming in.