Mrknowitall
Adventurer
Seems like the only customers for light-medium 6x6 (or 6x4)vehicles are military and Australian energy and telecom customers. If your criteria was to retain the narrower track of a midsize truck or older landcruiser while operating in the 5-7t weight area, it might be the ticket. On a big fullsize, going to high-capacity tires probably the better choice. I have to admit, I'm intrigued by the prospects of a 3rd axle, but the technical whatnot is very complex, at best. The now defunct USA6x6 company used to make transfer boxes that replace the pinion support on a Ford 9" or GM 14 Bolt.