I have a question i am about to buy a 3pk from a guy are there any major difference between the old silver 3pk with the funny looking wheel and the current 3pk and will the 2.4 modules and recievers work in the old one.

The FASST module will work on the old 1st 3PK.

does that mean if the 3pk has fm or synthesized module u can replace it with fasst module?

Yes. I have an orig 3PK that is FM. I swap between a FAAST module for certain RCs that I have set up to run 2.4. Mostly I use a FM synth module for most of my other RCs.

The flexibility is one thing I like about the 3PK and the way its configured.