Calcaterra
Donor
Your challenge, if you choose to accept it, is to make (and/or keep) the New York Mets a World Series contender post 1969.
The Yankees vs Mets rivalry will intensify, somehow.
What's the point of departure? Not trading Nolan Ryan will really help but might only get them the one more division in 1975 and I doubt they can beat the red since Cincinnati swept both League Championship Series and 75 and 76. But you said Contender so okay, they could probably swing enough trades to win the division both years but then lose to the Reds.
Before, however, you probably need them to draft Reggie Jackson. That gets them a division title in 1970 as well since they were only a few games out and that Reds team despite over a hundred wins is potentially beatable.