The 2.3L turbo engine was in the Mustang in 1979, the SVE version in the SVO Mustang came around 1984. The Turbo Coupe and Mustang GT/Cobra Turbo has the same engine. If you check a parts catalouge you will find very few parts in common between the TC and SVO engines of the same years. SVE may have had a hand from the beginning, but the 2.3L turbo has it's roots in the Mustang.
