What socket size is the nut on the axle that holds the hubs? I'm thinking 29mm or 30 mm, but am not sure.

 

Whatever's in the tool box and fits. LOL I think it's the same from my racer to my z and I just used a 1 and 1/4 inch. 1 and 1/8 was too small. I think that a 1 and 3/16 would be perfect, but the 1 and 1/4 worked and didn't strip it.

 

I put a 1-1/4" on it and it was pretty sloppy, but it was a 12point, not a 6. I'll try to find my 1-3/16, wouldn't you know that the one I can't find.
Where Bob Vila when you need the Craftsman man?

 

LMAO The one I couldn't find either!! The 1&1/4 worked for me. Probably was a 6, but I didn't even look. Just tried it, said good enough and popped it on the gun. You'd be a lot less likely to strip with a gun because you can keep it straight. I had no problems.