is it possable to sail a merlin with rear mainsheet and what year of production was 3221 many thanks.

lots of people do sail with rear sheeting not at the front of the fleet, but they do. 1980 ish?

That depends on the type of rear main you use, I have been using a twin bridal rear main for about half a season, and I move higher up the fleet because of it, less weight, easer to ease in gusts etc, watch this space, as i will be continuing with it this season.