Okay I have a problem that is not NEARLY as drastic, but my rear tires are wearing out unevenly. Except, the excessive wear occurs on the OUTSIDE, and only on the edge of the tire, so to speak. Rear left is significantly worse than rear right. I am also curious as to what it could be since there is no alignment that can be done on the rear axle. Very curious, as I now have a new set and don't want to mess it up.

 

Although, if your suspension bushings are badly worn you could have alignment issues.

 

Wear on both tires on a solid axle can only be a bent axle housing. If it was only on one side it could be several other causes but since it's about even on both sides points to bent axle housing.
Look very carefully at the housing for damage from a hard hit near the center, like it backed into a rock hard. Also look for cracks in the housing, although there should be oil leakage if there is a crack.
Someone mentioned it could have been dropped and that is also a possibility.
Has this been hauled on a trailer?
Is there a possibility that some careless trucker has chained the back axle down in the middle WAY TOO TIGHT?