The fully implicit 3D two-fluid MHD code XTOR-2F has been developed to allow an easy implementation of physical models beyond MHD. The numerical method of solution used in XTOR-2F is presented briefly. The code is then applied to the investigation of the long time dynamics of internal kinks, first within the framework of resistive MHD including thermal transport and next adding more refined effects such as ion and electron diamagnetic rotations and separate density and pressure evolutions.