What are the overtime rules for the nhl in the 1970'S?

In the 1970s, the NHL's overtime rules were quite different from today. If a regular-season game ended in a tie after 60 minutes, it remained a tie, as the league did not implement a formal overtime period until the 1983-84 season. In the playoffs, however, games continued with full 20-minute periods until a winner was determined, with no sudden death format. This meant that teams could play for extended periods until one scored, leading to some famously long games.