Did Quack Air have Jumbo jet? Yes
The Boeing 747. Quack previously have Boeing 747-100, 747-200B, and 400.

About Boeing 747-400 of Quack Air

Boeing 747-100 and 200B is already too obsolete to fly. In 1989, Quack finally placed order on Boeing 747-400. And finally in 2 month later, the delivery was made with first unit to be registered as N441QA (The one that suffered engine shutdown at Pacific Ocean due to ash of Mount Kīlauea , but the aircraft land safely after the crew restarting the engine after glide to safe zone), Quack Air became first Boeing 747-400 Operator in Duck Republic. It was the second largest operator of Boeing 747-400 in duck republic under Mallard Pacific¹ which have lot of 747-400. From 1989 to 1998, Over 12 747-400 was delivered to Quack Air.

On December 2019, Quack Air took the last flight of Boeing 747-400 from Tokyo Haneda to Duckburg International and all 747-400 retired and replaced by Airbus A350-900.
Most of the 747-400 are being stored and scrapped at Victorville, California except N441QA that got preserved af Quack Air museum, Quacker

¹This airlines inspired by Continental and United Airlines