Ron,
Blender is another free 3D modeling program. The galleries on the Blender website look impressive. I've downloaded and installed the program, but I have not actually used it yet, so I can't comment on how easy or difficult it is. There are a whole bunch of tutorials that you can view to help learn the program.
Blender
Tutorials
Mike,
Having done some 3D modeling (3D Studio Max) I can really appreciate the modeling you have done. Maybe some day I'll get around to making a caboose to go with your loco.
Dennis