An history of the Renault 20 TS (in French):
http://zorgblogauto.canalblog.com/archives/2012/01/19/15113273.html

This website applies in fact to a lot of cars that are or were sold in France, but production years and technical data sheets of the Renault 20 can be found here (in French too - maybe not exhaustive):
http://www.autoweb-france.com/fiches-techniques/Renault/all/