I would like to know if the DCX receiver in 27mhz can work with the Futaba 3PK with 27mhz module? I like the performance of the DCX receiver in my CRX 40mhz and would like to get one for my 27mhz Futaba.

It should work just fine with your futaba.

Thanks..... Do I purchase a Futaba crystal or Hitec?

A Hitec dual conversion crystal.