After the 1966-67 NFL football season, the Minnesota Vikings traded Fran Tarkenton for four draft picks in the 1967 NFL Draft. The Vikings used one of the four, a second round draft pick, to acquire Grim. He played with them for five seasons, helping them to the 1969 NFL championship and a Super Bowl IV appearance, before being traded with two other players and two draft picks as a part of the trade to the New York Giants for Fran Tarkenton. He played with the Giants for three seasons and the Chicago Bears for a season. Grim ended his career, playing with Fran Tarkenton and the Vikings for his final two seasons, helping the team to the 1976 NFC championship and a Super Bowl XI appearance. Grim ended his career having played in 133 total games.