A heavy duty excavator bucket is constructed with an exoskeletal structure comprising coupled cast components including a lip member, opposed wing members, junction members locatable between floor and side walls and side and rear walls and a cap rail structure extending between opposed wing members about the upper periphery of the bucket to form an integral structure. Steel plate floor, side wall and rear wall members extend between adjacent exoskeletal regions. The bucket may include a cast arch member extending between opposed wing members and a cast reinforcing member extending between opposed junction members adjacent said rear wall.