More info here
MergeSmoothing is a windows program that will read an FBX file and generate smoothing groups based on the normals of the mesh. It can read in earlier FBX versions and will output a 2013 FBX file. UDK wants smoothing groups and it wants version 2013 files. If both conditions are not met it will generate a warning message.
original ut3 characters translated for use with lightwaves fbx exporter.
The Doom3 scripts for truespace 7.61 will read and write idtech 4 md5mesh and md5anim files.
Some notes for working with trueSpace and the UDK. Exporting T3D, FBX, FBX for matinee, T3D terrains, PSK and PSA files. When complete will be a recipe for transfering a complete tS scene into a UDK level.
Unreal T3D file format specs no longer available from original source
Unreal Engine version 4.13.0 removed T3D import from the file menu because of crashes. Check the notes here for workarounds to continue using the T3D format in UE4
UDK Scaleform samples converted from Flash CS4 to version CS3