I have a shay that at the moment I would like to add Rail sounds to. The only thing is I would not like to add tmcc yet, that will come later. Can I use these three components in my shay to add rail-sounds that will work in conventional mode?
Theoretically, yes.
But you'll also need a speaker assembly, volume control pot assembly, 9-volt battery assembly, RailSounds/SignalSounds switch assembly (I guess that one would be optional), chuff switch assembly and mounting stand-offs for the motherboard.
You didn't indicate which shay you plan on upgrading, but they're known for being small with cramped interior spaces. Before buying a lot of boards, I'd advise you to proceed with caution, especially if you're unfamiliar with adding sound systems in general.
TRW