Looking for Fusion 360 file for 6384 motor mount with mast clamp

I’ve been searching this forum as well as grabcad/thingiverse for a CAD file for a 6384 motor mount with mast clamp.
So far I only found STL files.

The reason why I need a proper CAD file is that I need to modify it to fit a Lift mast.

Any leads?

Thanks for your help.