Though the GE GEVO is about 50 years too new for my 1957-era layout, I nevertheless had to buy the FVM NS Heritage NKP unit. And after my recent good experiences putting sound in my Atlas GP9's and RS11's, I decided the GEVO needed sound, too, and I thought that since many of you model the modern era, you might be interested in this project. So, here goes. I used my now-standard parts: an ESU LokSound with the GEVO 12-cylinder sound file and the Knowles Fox Speaker. An entire tutorial follows, but for those of you who want to cut to the chase, here's a link to the final product (be patient; the startup sequence for this loco takes about 35 seconds!): [video=youtube_share;NFzlQ_sdPzI]http://youtu.be/NFzlQ_sdPzI[/video] Now here's how I did it. Because of the size of this locomotive, I mounted both the ESU LokSound and the speaker at the rear of the frame. Very little frame modification was required - just taking off the "ears" that stick up at the rear end of the frame and sort of smoothing things out in a diagonal for the decoder. Here's a photo of the modified frame: Next, I cut off a couple of pieces of the light board to re-use. This photo shows the front section of the light board, which I used for power pickup for the decoder and for the front headlight/ditch lights as it comes from the factory. I also use another tiny piece of the light board with a 1K smt resistor to power the rear light - you'll see this in another photo. Next, I placed the speaker at the very rear of the frame, and glued on an SMT white LED on the back of the speaker enclosure to use for the rear light. If you zoom in on the next photo and look closely at the rear of the speaker enclosure, you'll see the tiny yellow speck that's the LED. The LED comes from Richmond Controls and has the magnet wire leads already attached. Since the speaker sits right under the radiator housing, I drilled a bunch of #80 holes in the housing for sound egress. Once it's back on the loco and you do even a tiny bit of weathering, these holes disappear. In the next message, we'll wire things up and test.