Jerry,
You are absolutely correct about the rear axle. The dual wheels were fake, actually worse than rigs equipped with single rear wheels. Using custom fabricated wheels, the inside of the outer wheel bolted to the outside of the inner wheel. That inner wheel bolted conventionally to the axle hub using just the typical 5 lug pattern. It was rediculous.
Our saving grace was that the Mirage weighed only 3600 pounds plus people & supplies. It was a very light weight rig. The rear axle never failed us. But self contained motor homes like the Dolphin, Winnebago Warrier, and the kind with full blown motor home features, they were in danger while still on the factory floor.
Those goofy rear axled motor homes were manufactured through 1987. In 1988 Toyota introduced true dual wheels paired with an appropriate heavy duty axle very similar to conventional motor homes. The problem went away, but the reputation stuck like glue.
For our 1983 Mirage, I replaced the rear duals with large single rear tire around 1986/87. After a number of years dealing with handling troubles, in 1995 I finally took the rig to a place who educated me on the free axle upgrade from Toyota. They provided a brand new 1995 rear axle assembly seen below, and me the labor. I had to sign a waiver stating I would never sue Toyota over this. When finished the rig was solid and performed great til the day I sold it.
Here is what Toyota provided free including shipping to the shop of my choice.
Here is the upgrade in 2007 when I sold the rig, a very conventional design, the right solution to a huge problem.
I found an internet picture of fake rear wheels. It isn't very clear, but look close.
This set appears to have a 6 bolt pattern but my 1983 had 5.
