OK, I know this subject has been absolutely flogged to death. I wish we could get simple, clear, non confusion-causing answers from the FCC but I doubt that it will ever happen. I remember following a thread similar to this a year or more ago, with many people far more knowledgeable than I contributing, and the conclusion was that the modification (I'm not advocating swapping crystals) ban did not apply to 27 MHz. A quick search of the FCC site shows that the ban (95.222) applies to type-accepted transmitters(95.209 refers to 95.222 and specifically mentions type accepted transmitters), and the 27MHz band, is non type-accepted as per 95.209. This rule does refer to technical specifications I did not look up. I'll just stick to 72 & 75MHz with synthesized transmitters and receivers to solve my problem. I guess that since the park flyers tend to be lower cost, manufacturers just don't pay attention to 27MHz with regards to more sophisticated transmitters.