Ditto, you cannot legally change the TX crystal on certified TXs. The 72MHz TXs for aircraft are certified. Other bands may or may not be certified. I believe the 75MHz band does not used certified TXs, so XTAL swap may be OK there, but don't take my word on this until you do your own research. But back to 72MHz, This has been beat to death, and as pointed out previously, there are always some who think they have found a loop hole. I have personal "Ins" to the FCC as both my parents work for FCC field monitoring offices, i.e they enforce the regulations. I've been thru this with them. There is no loop hole. The law is clear.

The industry is not in violation. The Hi/Lo band issue, which I believe only applies to Futaba gear, is on the RX, not the TX. TX will ship preconfigured for a certain freq, which is marked on the TX and the box; or it can use modules. You can change XTALs on your RX all you want.

Cheers.