Channel 80 is not an aircraft channel, it's a surface channel on 75Mhz. Since the crystal you have says 72.50, the "80" is something besides the channel.

72.50 is not a currently valid channel!! It's half way between channel 35 (72.490Mhz) and 36 (72.510Mhz) DON'T USE IT. I'm hoping you typo'd the frequency there. Could you check and see what it actually says?

If it actually says 72.50, then I'm not sure, but I suspect your crystal is really old. Sometime in the mid-80's, when the 72Mhz band was opened up, there were only a few channels, on rather wide spacing. Some of those old channels are now "between" our current ones. I think you have one of those.

I don't use Futaba RX's, I find that whole low/high thing to be entirely too annoying to deal with.

What cstevec said is right on about transmitter crystals and tuning, at least for most transmitters. And he is absolutly right about the FCC rules that make it illegal to just swap TX crystals. However, in other countries, it's not illegal at all. And, further more, some TX's are actually designed to stay on frequency with different crystals within their band (such as on 72Mhz). So, some TX's will NOT drift or cause anyone any problems or lack of range if you do, in fact, change the TX crystal. Now, which will and which won't is a hard call.

Either way, if you change the TX crystal, you are breaking the FCC regs, and if you have a crash that causes injury or property damage that is related to a radio failure, you can pretty much bet that your insurance isn't going to cover you, it will be considered negligent.