I'm just an 'oldie' that doesn't know zip about 9V, RC and/or PF trains.
My brick is made with the 'eighties' system in mind. Using the 1x6 brick and light prisms. Take a look at my third picture. If that'll fit into your train somehow, you're all set. My brick will work on 9V as well. Slightly less bright, of course, since 9V is less juice then 12V.