I have collected some of the best links from Youtube, so you can watch the Rally Corsa in g.4 rallies.
This is one of my favourites, Rally of Thousand Lakes 1981 and Markku Alen winning it with Fiat 131 g.4.
Here is a short cut from a -78 Rally of Thousand lakes and Timo Salonen with his Fiat 131 Abarth
Rally of New Zealand 1980
San Remo 1981, many clips of 131 with others