I am by no means an authority when it comes to identifying old trucks. I will admit, that I was stumped by a few I found in this old book. The following is one of them. It took a lot of searching on the net to find a clue - it came as another picture, the ONLY one I could find that would help identify the truck type.
First is the Zaffo illustration -

The only thing stated about this truck in the book was, it's called a Flushing Machine.
Second is the picture from the Internet - thanks Hank's Trucks and Ken Goudy.

Note the "suicide doors".