FWIW, here's a truck we saw at Macungie (PA) a few years ago. It appears to be a 1.5-ton, but still shows how they did the bed to accommodate the duellies. I don't think the outer fenders are factory

But interesting to see the inner fenders (which might be factory).
I can't tell you anything about the truck. I just saw it in the for sale corral and took the pictures.
John