On August 11, 1973 — During the Old Timers’ Game played at Yankee Stadium, Mickey Mantle homers off his old teammate and best buddy, Whitey Ford. After launching a shot that lands foul in the upper deck, the slugger sends the southpaw’s next pitch over the fence, much to the delight of the large crowd gathered for the festivities.

Source:
Baseball Reference August 11
National Pastime
Retro Sheet
Hall of Fame
SABR Games Project
Replay The Game