The former United defender thinks they would have beaten every team in Arsenal history.
Writing in his new autobiography '2 Sides,' the 35-year-old talked up the ability of United's 2008 side, which won the Premier League and Champions League that year.
The presence of Cristiano Ronaldo, Ferdinand believes, separated that team from any other in United history.
And it would have beaten any of Liverpool or Arsenal's greatest sides too, he claims - even the 'Invincibles.'
The Gunners side of 2004 that went unbeaten in the Premier League, however, would have provided them with their 'toughest game,' in his opinion.
"If you put our 2008 team up against any team in the history of Man United, I think we'd win. We'd overrun any of them and we had magic in Ronaldo the other teams just couldn't stop," Ferdinand wrote.
"Think what we had up front: Ronaldo and [Wayne] Rooney with Carlos Tevez backing them up.
"And not just the United teams. I think we'd have been too quick for the great Liverpool teams of the '80s and '70s.
"We'd have too much firepower for the best Arsenal sides, though their 2004 'Invincibles' would have been our toughest game, because they were a strong, physical, quick and intelligent side - and, in Thierry Henry, they had a guy who could create something from nothing."