I was at the pick a part salvage in okc and there was a 89 supercoupe that had stamped steel lower rear control arms. I thought all birds were cast iron but this car had stamped steel ones the only one I ever saw. I don't know if it was a one year wonder or maybe ford used a different supplier for a short time. The car was manufactured in the 4 month of 1990. It also had a hollow rear anti sway bar.