I can't believe I wasn't able to look it up in the Service manual, (no size on the tool used even...) OR here, OR looking up the part on line (No one listed the 4WD nut...)

It's likely 50mm or above the manual says its Hex. but I want to know so I can see if I have it already or if I need one. (before I need it. I probably have a half dozen or more sockets for different size type 4X4 axle nuts, but I just KNOW if I wait until needed, it will be a size I DON'T have...)

(Eventually I'l have a list of all the tools/sizes needed for this thing, but I'm not there 3 weeks in... at that point I'l assemble yet another "Rand box" for those tools...)