All I have is the snippet from the Swiss Automobil Revue 17/1984. A brief translation:
Carrosserie Winiger from Frauenfeld, Zürcherstrasse 250, has built a 7-door VW Golf Turbo-Diesel on occasion of their 35th anniversary. For this a stock Golf was elongated 92 cm and received two more doors. Emphasis was put on strengthening the bodywork, sills and roof were reinforced with tubes and several stress tests were done. Only stock VW spare parts were used. The 473.5 cm long car is road legal.