[Espeefan]

You can run older servos with a newer radio, but you won't be able to mix and match receivers to new radios, unless they use the same frequency and channel. Like Joe already said, FM technology will work with other FM technology, but this newer 2.4 giga-hertz technology is only going to work with like equipment. Servos are usually pretty universal. Some servos have plugs that are more universal and will work with other brands of radio gear, and some companies prefer to use a unique plug that doesn't work with anyone else's receivers. You just have to double check before you buy.

On the subject of radios with three position toggle switches, many offer this. Usually if you buy a radio that features helicopter programming, they all have a 3 position toggle switch. With helicopter programming, the three position switch is normally assigned as your 'idle up' feature. You can use this to shift the servo on a 3 speed transmission. It's great, and a important feature to watch for, when you shop for a radio. Many airplane radios use the 3 position toggle switch too, but you have to be more careful. They don't always have it. A lot of times, the same radio will be sold for helicipters, or airplanes, and only the programming and throttle stick is different for each. So both versions will have a 3 position switch.

My Futaba radio has more then just one 3 position toggle switch. I forgot just how many it was in total, but I want to say 3 or 4 of them.