I have two locomotives that I want to convert to DCC with sound, one is DCC ready, the other has DCC for speed, direction, and lighting. there are versions of both available with sound, but they were not available with sound when I made my purchase, I have the diagrams of both versions (Downloaded from here today) Can I just order the parts through my local hobby shop or directly from Bachmann or would I have to go with after-market parts? and If I have to go aftermarket, I would like recommendations...