A guy on one of the Large Scale forums has a series of photos of a Keystone steam-powered excavator. This was the first "backhoe" type of excavator, and used the same frame and engine as on their popular drilling rig:
http://s397.photobucket.com/albums/pp52/steamnut1917/KeystoneEscavator/ (http://s397.photobucket.com/albums/pp52/steamnut1917/KeystoneEscavator/)
Ray, The escavator is neat :)