I've heard you canswap the transmitter and receiver crystals in a 27mhz radio and it will act as a new frequency. Is this true?</p>

yep, just make sure you have the same frequency in the transmitter and receiver.

It's true but only to a point.
First, they must be the same frequency band and modulation type. 27mhz crystals must be replaced with 27mhz crystals, 75 with 75, etc. AM crystals will not work in an FM system
Second, any new crystals must be compatible with the radio equipment they are going into. Not all crystals are compatible with all brands/systems.

Also, it will not "act as a new frequency" it will be transmitting/receiving on a new frequency. So, if you and a friend both have RC's on the "Red" (A2 or 27.045) channel one of you could put in a set of "Green" channel (A5 or 27.195) crystals and you will no longer interfere with each other.

Welcome Pilgrim, I think they may have misunderstood your question.

I understood it like this "switch the RX crystal with the TX crystal" Yes, switching (swapping) them will yeild a "different channel" I'm not sure it is legal, or what the new freq is or if it is far enough away from the originals to be safe. I would think it falls somewhere in between the original 6adjacent freqs.

I'd like to know :for example if we did it to channel 3 would the new freq be right next to channel 3 and 4? 3 and 2? maybe it doesn't change freq at all? I'm not sure how it works, but I am sure that it does work.

guver, you are right, I misunderstood the question.
I've not heard of switching the rx and tx crystals. I don't know if it will work or not, it very well may. I am sure that, as far as the FCC ios concerned, it is not legal.
You should be able to tell where the "new" channel would fall by looking at the frequency imprinted on the rx crystal and and compare that to the existing channel frequencies.