I screwed up the mnting lugs on my 3305 and needed a new top case. I have in my stock and TowerPro sg5020 servo. The 2 servos look alike except the Futaba has metal gears the other plas. I discovered that the TowerPro case and Futaba are the same size and interchangeable so I switched cases and labels and it is a perfect fit.You can buy a towerpro servo cheaper than a Futaba replacement case. Thought some of you guys might be interested in my discovery.