I have a number of the Spectrum 4-6-0's. I model the Tonopah and Tidewater RR and they had a number of locomotives with 62 inch drivers but with straight walkways and only 1 air pump. The low boiler model looks about right. It looks like a simple conversion but I was wondering if anyone has tried switching the superstructures on these frames, before I take a screw-driver to mine and try. If no one has, I'll give it a go and report back.