I realize this is near-ASB, but maybe with a sufficiently earlier POD you could move the correlation of forces in Argentina's favor, but not so much that the UK still tries to take back the islands.
I had actually thought of something like "DBWI the UK keeps the Falklands", but I realized that the likeliest route to a Malvinas is that the Foreign and Commonwealth Office just gives them to Argentina, and in this alternate universe no one would really care enough to post the topic for discussion.