The story was originally published in 1979 under the title "The Ghost Pony". That is how I remember the story (I read it in elementary school and it has stayed with me this long) and I spent many years looking for a copy of the old book only to find it was republished later under a different title. No wonder I couldn't find it! *grin* So....if you are looking for "The Ghost Pony" by Lynn Hall, this is the same story.
My 11 year old liked this book.