Apparently I wasn't completely clear on the dual rear wheels. The 1-1/2 ton Stake Body truck in 158-1/2 inch wheelbase only came with dual rear wheels.
This excerpt from the Vehicle information kit (with my highlights) gives you the full information.
Rear auxiliary springs are typically stacked on top of the standard springs and contact frame brackets only as the truck is loaded to compress the suspension. There's a figure of Aux springs on page 37 (PDF page 40) of my original link.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.