RE: Changing frequency
Here's a spoon to stir that can of worms you just opened.
Legally you can't change your tx crystal w/o sending it in to get tuned UNLESS your using the plug in RF modules that the newer Futaba transmitters use. FCC rules regarding type acceptance, AMA liability issues etc.
Do a search theres PLENTY of info.
If your smart, the safe way to do it is replace the crystal so that both recievers are on channel 20.