Hi Lou

An NMRA 21-pin decoder will be the choice. The choice is wide.  One of the less obvious things will depend on your intentions and willingness to work with the locomotive.  Do you solder or want to learn how to solder?  Do you want more than headlights and reverse lights?  Do you want a stay alive? Is the speaker included with the locomotive?  Some of these things are more easily achieved than others.  I chose to have more lights and manufactured a means to achieve all the above wants in a locomotive on an easy to solder printed circuit board with a jack for a 21-pin connector and a small connector board that allows me to separate the shell of the locomotive from the frame.  You might consider saving the shipping when you order your decoder and subsequently save some frustration.

Scale Sound Systems

If you bought a non-sound Walthers Mainline GP9 you'll need to add a speaker.  The frame is designed for either a 25mm or 28mm round speaker, I forget which because I used "sugar cube" speakers in mine (with ESU LokSound 5 decoders).  However it took a little fiddling.  SSS makes a drop-in enclosure using a sugar cube.  I'm told that as nice as mine sound the SSS speakers are even better.

Scott Chatfield

Nick/Scott,   Thanks for the

Nick/Scott,

Thanks for the replies. I definitely want to add some extra lights, sound, and a KA. I solder and don't mind working on the electronics. Which decoder buddy do you recommend?

Lou

Hi Lou

If your locomotive has a 21-pin decoder holder in it already the V5 or V5B Decoder Buddy should work fine.  If you go with LokSound the V5B is the best choice due to the pad for the white control wire of the Power Pack. It comes in the Green package and has the W pad labeled on the row of pads on the lower right hand side of the printed circuit board.  

I am also very partial to Scott’s suggestion of Scale Sound Systems speakers.  They are in all my locomotives now.

Enjoy!

Thanks Nick, time to do some

Thanks Nick, time to do some shopping!

Lou