Heat grill. When ready to grill, oil grill rack. Alternately thread 3 scallops and 2 shrimp onto each of six 12 to 14-inch metal skewers; reserve butter mixture. Place kabobs on gas grill over medium heat or on charcoal grill 4 to 6 inches from medium coals. Cook 6 to 10 minutes or until scallops turn opaque and shrimp turn pink, turning once and brushing frequently with butter mixture. If necessary, reheat butter mixture before brushing on kabobs. Bring any remaining butter mixture to a boil; serve with kabobs.