72mhz is the spectrum of all the freq's between 11 and 60.

Here is a [link=http://www.futabarc.com/faq/frequency.html]frequency chart [/link] that might help explain it better for you.

Unless you have a radio with a fequency module, it is against the FCC regulations to change the transmitter crystal.

If your on channel 12, you just buy crystals for all your receivers for channel 12.