I had both the original Autocar dump and the A64B tractor. IIRC, they are quite different. The spacing between the rear axles was different, I was converting the glue-bomb tractor kit into a mixer with large tires and I recall taking measurements of both and discovering the tractor kit had a shorter distance. I don't recall suspension types off hand, though I could probably dig them out. Not sure if the later A-car dumps changed, I' only had the original.