Raym,
The #2 is their oscillating engine, the #3 is a smaller mill engine, and the #5 if the coke bottle engine. My only point was that I had purchased the casting kits back before they started using more cast iron for many of the parts. All of those now have some cast iron parts in them. The bronze machines so much better though and I am finding the CI castings on the #1 pretty rough by comparison. Maybe its a different foundry or something.
Bill