The stock radio box is pretty good, I siliconed it's seal. I am using a traxxas xl-5 esc, which is waterproof so begin with, and that's all you really have to worry about. The motor is fine to be submerged, just oil it afterwards lightly on the bearings, or not. I just let mine go, it's a cheap stock motor and I want an excuse to replace it. The steering servo should be okay, you can purchase a water proof one if you kill yours, but like I said, they usually are fine to be submerged. The connectors and battery, don't worry about. That just leaves the gearbox and axles, just periodically open them up and change the grease, just like a real truck that you take mudding. If you do not want to purchase another aftermarket speed control, you can just silicone the edges, or open it up and fill the case with silicone and re-assemble it with it oozing out each hole, then wipe off the excess and make sure the heat sink is clear of anything. If you don't have a radio box, you can just put the reciever in a balloon, and silicone it. There isn't really any science, you just take what looks vulnerable, and seal it with whatever you can.