I won't get into what works or doesn't work but I will say I have been using the Hitec HS 81 for years without a failure. I used them in race planes for the ailerons and throttle. At the moment I have a class-C pattern plane and I use one for the throttle and one for the nose {trike} LG for steering. They have proven themselves to me to not be effected by the vibration of a glow engine. They can be had with metal gears but the nylon gears have worked for me. Tower doesn't make anything, they distribute products with there name on it. I still have several of there servos on hand from days gone by, I think they were made by Futaba.