Actually Dean,
The two engines that were shown together were made for two different types of people.
The lightweight flywheel one was for little children to use, the slots and holes in the flywheel kept little fingers safe, whereas the larger one was for a gorilla sized friend of mine.
The last triple set I made were for two very good friends of mine and the third went to my late wife. She played with it almost every day, and when she left, it was given to my nephew for safe keeping within the family. Nothing is safe with me you see, I tend to give everything away at a moments notice.
John