Converting my dully to a 10 wheel drive to handle Toyhauler

Over in the Truck Campers section of the forum, right now there's a post with pics of an old duece-and-a-half military 6x6 truck with a motorhome body on it. Both rear axles are driven. A rear axle set from something like that would be good for your project so you don't have to re-invent the wheel trying to figure out how to couple your two Dana 80 rears.