I don't think it is either Ives or Marx.
It looks like a self-contained 2-rail truck. the sideframe castings look like bronze. I don't think either Ives or Marx ever did 2 rail. It is an AC or DC motor?
I have never seen what Adams and Sons put in their diesels, but that might be a possibility. The sideframes are definitely a representation of the EMD Bloomberg truck. Adams and sons made kits for a number of EMD locos I think.
It does not appear to be ALL Nation or General Models. I have seen a lot of their mechanisms and never saw one like this.
Just some thoughts.