Is the Futaba 3GR-FS 2.4GHz Transmitter compatible with the R604FS Receiver.

[lucas-b4-b44]

Is the Futaba 3GR-FS 2.4GHz Transmitter compatible with the R604FS Receiver.

I have the 4PK and you can switch between C1 mode for 3 channel and C2 mode for 4 channel.

So does this mean you can't bind the R604FS to the 3GR-FS?

I would like to know as I recently sold a perfectly (tested before sending)working R604FS receiver to someone with a 3GR-FS and they are having problems binding it.