The 91 Cougar XR7 was the only 5.0 car that came with the ARC. Swapping it in is probably more trouble than it is worth. There is a provision in the 5.0 tbird computer to run the ARC, so you would have to run an additional wire to the ECM, as well as the install the computer for the ARC, and run the entire ARC harness which has to go basically through the whole car. Plus even after you do all this, they don't make the ARC shocks new anymore, so you would have to install old shocks that may be worn out and not perform as well. Your best bet to improve the handling of a 5.0LX tbird would be to get SC springs, eithe SC or Addco sway bars, and run sport front shocks and 03 cobra rear shocks. That will provide a very similar ride and handling to the SC, and you won't have to go through all the trouble of swapping everything over.