3ds to x_t conversion is typically searched by users that are searching for options how to convert 3ds Max content to Parasolid format (.x_t), which is something that is not supported in 3ds Max by default.
You pretty much have two options, either use another exchange format (like FBX) to transfer the content to software that does support, or find a dedicated CAD/3D converter that will allow you to do this in a single step.