Here's the 1975 Riviera GS that board member 75Riv (Rob) owns nowadays. It was advertised back in 1992 (31 years ago) in a nationwide old cars magazine, when we used to pay with Dutch guilders: Another, even older, advertisement with a lower asking price: Photo of the car when Rob already owned it (2004) This is how the car looks nowadays after a respray and new vinyl roof, I took this photo at a car show in 2006:
Here's a YouTube video about the Wizard-Control for the 1932 Buicks, as mentioned in the Dutch advertisement above.