When the American League expanded in 1961, the season was changed from 154 games to 162. In 1927, when Ruth hit 60 home runs, he played in 151 of the 154 games. In 1961, Maris' record-breaking year, he played in 161 games.
Ok, so a season was 8 games more.
His 1921 and 1927 seasons are the two best ever. Look at these numbers:
1921: Avg. .378 HR 59 RBI 171
1927: Avg. .356 HR 60 RBI 164
Damn.