Originally Posted by AreCee

DSM2 is the newer type of signal proccessing used by Spektrum. It is not compatible with DSM (the original proccess). So any DSM module will only work with any DSM receiver but not a DSM2 receiver. However, any DSM2 transmitter is backward compatible and can talk to both DSM2 and DSM receivers.

There are no DSM2 modules for Futaba/Hitec or Airtronics as far as I know.

The OP's problem is that he wants a Futaba 3PK/3PKS but all his receiovers are DSM2 which means that the Futaba with a DSM module can not be used with those receivers. He would have to get DSM receivers for it to work with the older radio.