well these type of clockwork Thomas models don't fit HO track as the wheels are rounded and look very different but an older clock work Thomas I saw can go on HO track. green 0-4-0 does work and seems to have no problems I have a load of HO track somewhere so I might try that as for HO I don't find it often but when I do and its at a good price I might pick it up. I got a few pieces of rolling stock that came from a starter set
I liked tomy ever since I found out about it