NameOfTrack-src.ac file in Blender via "File > Import > AC3D (.ac)" NameOfTrack-src.ac file and textures to the fitting category folder of your Speed Dreams installation at "speed-dreams-2/tracks" NameOfTrack.xml and change the line <attstr name="3d description" val="NameOfTrack.acc"/> to <attstr name="3d description" val="NameOfTrack-src.ac"/>NameOfTrack-src.ac