Not sure but it was the '98-'99 season when the Spurs beat the Knicks for the title. And I believe it was only 50 games long.
Because the players union, and the league could not reach a new collective bargaining agreement, thus the NBA season was cut short because the players didn't play until the agreement was in place.
Wow being a fan of the NBA since 2001, it`s weird to see something like this happen looking back on it now.