ASC also built and engineered the reintroduced 1983 Mustang convertible, but due to a higher than expected demand, Ford took over its manufacture in 1984. A longer-lived Ford-ASC project was the ASC/McLaren Mercury Capri and Ford Mustang which debuted in 1984.
The common story at the ASC site is that a Mustang was converted and presented to Ford because the wife of the designer worked at Ford and not allowed to park her Mercedes convertible up front (reserved for Fords). Ford turned them down as they already had a deal going with Cars and Concepts. Maybe Ford thought they could not make the volume needed. ASC ended up making 1 million convertibles before closing. I wonder if Ford ever made that many?
I have never seen or heard of a 79-83 Mustang convertible made by ASC. Other companies like Bivouac, yes and they only made 130 or so cars.
Just because its posted on the internet does not infer that its factual. The Coachbuilt article mentions Sandy Block as a resource. While Sandy was very knowledgeable, he was only so, due to his love for the ASC cars and a couple of friends he made at ASC. Sandy was a great friend.