O'Shea made over 250 appearances for United before signing for the Black Cats in 2011, and the Irishman feels that the current squad is on par with any side during Ferguson's 27 years at the helm at Old Trafford.
"The manager has been fortunate. He's had some great squads to select from but there's no doubt this squad are up there with the best of them," the Daily Mail quotes O'Shea as saying.
"The manager has got pretty much everyone fit and they'll go from strength to strength."
The Red Devils are currently top of the Premier League, but were knocked out of the FA Cup by Chelsea this afternoon.