Production of the 3 litre ceased during 1981 according to wikipedia:
http://en.wikipedia.org/wiki/Ford_Ca...2.80.931986.29
With five years added to the homologation that would mean a cut-off date in 1985 or 1986 (depending on production numbers during the final period of production) for the car in Group 1 or A. Here in Denmark 3 litre Capris were still racing in the combined Group 1/A championship by 1984 and Brian Chatfields BTCC cars from 1985 has been mentioned here as well. So, I would tend to disregard my previous post.
Jesper