Cretors made the original popcorn engines for their popcorn/peanut wagons in the late 1800's and early 1,900's.
Bob Pearson in Kansas obtained the original Cretors patterns from the factory in Chicago, perhaps in the 1980's, and he made new Cretors No. 01, 02 and 06 castings from the original Cretors patterns, and may still offer these castings for sale.
Bob Pearson's castings are interchangeable with the original Cretors engines from the early 1900's.
As I understand it, the Coles Cretors-replica No.01 engine used original Cretors engine parts as patterns, and so the Coles Cretors-replica engines are smaller than the original Cretors engines by the shrinkage factor for the metal used.
I have not heard of Norbert Keeley kits, and so I don't kown how they fit into the Cretors story.
If you plan on interchanging old/original Cretors and newer Cretors-replica parts, be aware of the dimensional differences.
.
