Ok, I will try and make this question as short as possible..

I have a
4pls t-fhss tx
3pl fhss tx
r304sb t-fhss rx
r2004gf fhss rx.

The r304sb Is in my short course truck.
The r2004gf is in my 8th buggy.

Both will be mainly controlled by my 4pls. But if I have a instance where I want to run both at the same time(providing I had friends ). Could I bind the 3pl to the r2004gf for the friend to drive then rebind to the 4pl and keep trims, and other settings on the 4pl?

Correct, just make sure you've created a model memory for that car on your 4pl and it will go back as it was when you re-bind.

the model memories are stored on the controller,
make 1 for each car, on each controller
bind by with the car and controller on
place the controller right next to the reciever, and push the bind button on the reciever

3pl will work with the r2004gf, but not the r304sb
http://www.futaba-rc.com/receivers/f...ss-compat.html

Thanks guys! Yea I know that combo wont work. But as long as I can run both at the same time and keep settings I'm happy.