Make sure you get one thats ballbearing with metal gears look at the torque output the stock servo has and you can go with a little more and you should be fine.Avoid crashing into things it will eventually kill any of them!: I like futaba just make sure what ever you buy is compatible with your radio.
I replaced the steering servo with a Hobbico digital BB servo from Tower hobbies for about $40. It's rated at abpout 193 Ozs @ 6V, nearly double OEM. I had it for about 3/4 gallon with no problems. Heres the link :
Do you need it to be waterproof? As far as i know traxxas is the only people who have waterproof but i dout u need it, just though i might through it out their.
i really like my Savox sc 0252! its not as powerful as above stated servo but still works great. another important thing for me is it
fits traxxas horns.
Savox doesn't carry any servos that are o-ring'd for water resistance. I sent them an email to find out after I saw them posted in this thread. Kind of sucks... I'd pay a little more for a better sealed servo.
I got one off of ebay for $34.00 w/shipping. It is a no name brand metal gear/ digital. According to the spec. 208 oz. never turned so well and quick. I feel it was a great deal for those of use trying to keep the hobby and the wife at the same time.