If your receiver is really on 50 MHZ (ham band) and you have a HAM license, it it legal to use on either cars or planes and, I believe all 6 meter transmitters are positive shift, even the Futaba and Hitec. Note: I said legal, not recommended. If you want to go with the HAM bands, stick with the 50MHZ for planes and use 53MHZ for the cars and boats to minimize chances of being shot down with interferance.