I just finished putting a Digitrax 123K3 decoder in a Kato N Scale NW2 switcher. The Digitrax instructions were easy and straight forward. However before starting the install I also looked at a youtube video. Big mistake! I should have just followed the Digitax instructions. The youtube video showed the guy removing the fuel tank first which is not a part of digitax instructions. The fuel tank on this loco holds the whole thing togther so when I removed the fuel tank the whole loco fell apart and I had a terrible time getting it back together. I did get it back together and the new decoder works like a dream. The loco is kind of noisy but hoping this improves after break in. DO NOT REMOVE THE FUEL TANK ON THIS LOCO. It's not necessary and you will have a mess.