It is illegal to change the Transmitter crystal yourself because the radio needs to be tested and retuned at the same time to insure that it is at the frequency that is indicated by the crystal, and not bleeding over into other channels. I was once quoted about $50 to change a transmitter from one 72mhz channel to another, it may be higher to go from one band (75mhz) to another (72mhz) Unless you have a high-end transmitter, it may be cheaper and simpler to pickup a used 72mhz radio on the auction site. They usually go pretty cheap.