Ferguson says he was confident he was leaving United in good hands, with the club's emphasis on bringing through young players.
United also won the inaugural Barclays Under-21 Premier League, beating Tottenham.
He said: "It has always placed a great emphasis on youth long before I came.
"Sir Matt Busby started that and took Manchester United into Europe, the first English club to do so.
"It's always been there and I have tried to maintain that though it is more difficult in the present climate - you have to scout abroad now but you are still looking for young people who can do well."