Lee Mazzilli to the Rangers for Ron Darling and Walt Terrell

From The Met Wiki

Maz, the Italian Stallion (hey, these were the Rocky years) was the Mets' big hope in the late 70s. And his performance in the 1979 All-Star game (9th inning game tying homer, 10th inning walk-off walk) was the Mets' lone bright spot in the six dark years between the Seaver trade and the Hernandez trade.

But Maz never quite developed the way the Mets hoped, and the Mets managed to get two excellent young pitchers for him. Ron Darling was a key piece of the 1986 Mets. Walt Terrell was traded for Howard Johnson, who was also a big piece of the late 80s Mets, somehow captured best in Mets' pictures as the on deck hitter to Mookie Wilson, advising on the two scoring plays of the most memorable at bat in Mets history. To make the picture complete, Lee Mazzilli himself returned to the Mets in 1986, and himself played key roles in the final World Series games. He had to change to number 13, as his old number sixteen was now being worn by the team's biggest star, Dwight Gooden.

One of the best trades in Mets history, and even with the happy epilogue of Maz's return.