Part 4066 is a Duplo 1x2x2 brick. I'm wondering primarily about naming conventions. This part comes in two versions. The newer version allows a Duplo top-center stud to bind in the center, and the old one doesn't (it has a supporting structure in (...) (23 years ago, 3-Apr-02, to lugnet.cad.dev)
(...) I'd go for either option #1 or #3. In option #2, it seems like the name for 4066b.dat is misleading, because the difference between the parts is (relatively) minor. And I'd actually lean toward #3, because the difference is in the (...) (23 years ago, 4-Apr-02, to lugnet.cad.dev)