Hello I'm looking to buy some F model locomotives (Athern Genesis). But now I see online selling F3/F7 and F9 locomotives. Can you please explain: what is the difference between the models F3/F7 and F9 ? Thanks

I have an old Athern GP38 bluebox with the old style light board and I want to install a Loksound select decoder in it. I assume I will have to hard wire it in place of the light board - correct? Any help is appreciated.