Picked up by the Montreal Canadiens in the inter-league draft the following season, Maniago underwent a lengthy apprenticeship in the minor leagues, spending the better part of five years on the farm.

Maniago competed against Ed Giacomin and Don Simmons for the starting goal position in 1966, playing 28 games for the last-place team.

"[1] Giacomin firmly won the job the next season as the much-improved Rangers made the playoffs, and Maniago played in just six games as his backup.

One of his best years was his first with the team, where he had career highs in wins and shutouts while leading underdog Minnesota into the 1967-68 West Division semi-finals.

Maniago retired with 190 wins in 568 games, recording 30 shutouts and a career 3.27 goals against average, leading Minnesota goaltenders in every meaningful statistical category.