Update: The new version of Autoconverter allows you to convert FBX file version without modifying the internal structure of FBX model thanks to the new Convert menu command.
Convert Autodesk® AutoCAD® Files to 3D PDF and OBJ. The entire process is not very smooth, mainly because FBXs official documentation is not very clear. Choose options based on your need Click Save. I have wanted to make an FBX Exporter to convert FBX files to my own format for a while.
How to convert Filmbox FBX file to older or newer file version step by step tutorial. Convert Filmbox FBX file to different file version