The harness adapter.. cheap cheap cheap.. at least compared to what I paid at Best Buy for my car.. this is the vender I used with the wife's roadster..

http://www.ebay.com/itm/SCOSCHE-1986-UP-VOLKSWAGEN-WIRE-INSTALL-HARNESS-VW01B-/360844802136?pt=US_Wire_Harnesses&hash=item540406b858