The Zimmer Golden Spirit was built on the Fox body Mustang. I worked for Zimmer back in the 80's and ran various departments in the manufacture of this $64,000 (1984 dollars) retro-vintage-automobile.
Every body section was removed and disgarded except the doors and roof. We extended the chassis 44" and widened it by 18". At the time, Ford couldn't pass emitions requirements with the 5.0 engine mated to an auto trans, but we could. So, we'd replace the 4-speed manual with an auto transmition. The 5.0, back then, turned out a whopping 175 HP.
The remainder of the vehicle was all fiberglas that we molded in our plant (located in Pompano Beach, Florida). The interior used Recaro seats and special very expensive mouflon carpeting. The dash had real wood panels, and a Blaupunkt music system. We used real wire wheels and gold line tires. It was quite a car.
It took approximately 30 days to build one car on the production line, so we turned out one car each day. All of the Golden Spirits were sold before they were built.