Ferguson retired in May 2013 after publicly anointing David Moyes as his successor, but the former Everton man lasted just 10 months and guided United to their worst Premier League finish.
Van Gaal was the biggest spender in the summer transfer window bringing in over £150 million worth of new talent, including new British record signing Angel di Maria - while he also offloaded 14 players.
In quotes carried by the Daily Telegraph from a forthcoming MUTV documentary, Ferguson said: “Louis van Gaal has made a lot of changes and, thinking about that, actually maybe he’s doing the right thing, to clear the decks and build his own team - because he’s got the experience and coaching ability to do that.”
Van Gaal endured a difficult start to his Old Trafford career with his side’s defensive problems highlighted by a dramatic 5-3 defeat at Leicester last month.
But since that loss United have defied a mounting injury list to secure successive wins over Everton and West Ham and move up into the top four.