My son has a 1998 JEEP Grand cherokee and we are trying to replace the right rear wheel seal and bearing but I cant figure what size the bolt is holding in the center pin (KINGPIN ??) on the rearend looke like maybe a 6 or 8 mm (12 Piont)but I cant get either on it, any help would be very welcomed, also cant get any info from jeep on the size unless I buy a whole rearend.

 

The last one I removed was a 1/4",no mm would work,I used a socket,also had wrench just in case.