This is one of the earliest RUF VIN cars I have ever seen, having a completion date of 06/85. If you have any further information on it, please e-mail me at firstname.lastname@example.org
May 2014: Found sale information on vehicle on Jota Garage website. According to the description on their site, there are around 30 RUF VIN BTR coupes, but less than 10 cabriolets.
Photos courtesy Jota Garage.