I recently bought an Optic-6 2.4 Gz radio & I was able to swap the 2.4 Gz module into my Prism 7X & also use the Spectra module from the Prism 7x to convert the Optic-6 to 72 Mz.
Way back when, I bought 2 Prism 7xs to use W/a buddy chord for training. One of them was damaged by a thrown prop that took out the display. I saved the Spectra module so now I use both the Prism 7X & Optic-6 in 72Mz W/the original buddy cord from the Prism 7x radios.
Kudos to Hitec for forward thinking design when the developed the Prism 7x & designing the Optic-6 to be compatible W/the Spectra module.