MakerBot Print is our newest print-prepration software, which supports native CAD files and STL assemblies,
allows you to interact with all your printers via the Cloud, and many other exciting new features.
i just checked both rear diff versions 40mm and f1 version and both are correct inside of Slic3r. i don't use cura.
i would just rotate the part 90 degrees so it sits upright. the heavily angled spokes with bevel for the bearing goes down to the bed.