I have a work in progress building a concrete mixing plant, somewhat modeling the Spartanburg, SC Metromont plant that has an raised ramp rail line to allow hoppers to drop their load into pits, and using the Lionel 397 coal ramp for sand and aggregates instead of coal. I needed an O scale size concrete mixer truck to have something for my imaginary plant to load its mix into for delivery somewhere. I tried several things in the Amazon search box, and found a couple sets of 1:50 scale trucks, one was a concrete truck. These are very nice looking, lend themselves to repaints or use as is, and in one case around $20 for a set of 3, a dump truck, mixer and a truck mounted back hoe. Not sure of the linking policy here, but just put 1:50 scale cement truck in the Amazon search bar and maybe you can find something useful.
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