RE: Hitec module, Futaba radio, Airtronics receiver
In the US Futaba Tx's are negative modulation shift only and your Airtronics Rx's are positive modulation shift only. It makes no differance if you use the legal module in that Tx or a Hitec.
If you want to continue to use your older Airtronics Rx's and upgrade your Tx then you can use any Airtronics, any JR tx or Hitec Optic 6, Eclipse 7 or the older Prism 7x.
John