The new cover (1956) showing two diesel engines, the original cover (1954 ?) shows one diesel and one steam engine. 1959 edition has the two diesel version.
Edition with one diesel and one steam engine was seen on eBay with a 1962 date.
The story begins on the inside front cover and ends on the back cover.
Unknown at this time if interior art on 1962 edition is changed to match the new cover. Original interior art shows and discusses a steam engine.