Roger Maris in 61 I believe.
Through the 2010 season, that would be Roger Maris who hit 61 home runs in 1961.
Babe Ruth has the most career home runs as a Yankee with 659.
Mickey Mantle hit the most home runs at the old Yankee Stadium with 266.
Babe Ruth hit 659 as a NY Yankee.
Bernie Williams hit the most career postseason home runs as a Yankee with 22.
Babe Ruth hit 659 of his 714 home runs as a New York Yankee.
Don Mattingly had the most hits in a season as a Yankee with 238 in 1986.