Some thoughts about heavy trucks... In the forties and fifties there were still more regional builders than nation wide brands. By that time International Harvester, Mack, and maybe White were nation wide, but as a kid growing up in Chicago, I never saw Kenworth, Peterbilt, or Brockway or Marmon tractors, and likely nobody outside of 250 miles from Chicago ever saw Hendricksen or Diamond T. So pay attention to what brands were popular in your modeling area.

For a real oddball transit mixer, when I was in high school during the sixties, Material Service Corp., a big Chicago area concrete supplier, had made a deal with Carrier Crane Corp. to supply chassis for their mixers. These had the standard single person cab and low engine bonnet used to clear the boom on a mobile crane, not needed in the mixer application but there just the same.

I googled "Carrier Crane transit mixer" and come to find these must have been more common than I thought. The links to youtube videos have some good detail shots of a mid-sixties mechanically driven mixer drum.

https://www.youtube.com/watch?v=UEVNnyqU-Bg
https://www.youtube.com/watch?v=bX2WmyQG1ZQ

Dennis Storzek