To All: As most of you realize, SoundTraxx produces decoders for various companies with specific features and relative CV's that are specified by them (the company). Most of the CV's are the same but some specific ones aren't. There is a set of Manuals written by SoundTraxx specific to Athearn locomotives. They can be accessed at: http://soundtraxx.com/factory/athearn.php One specific example are the horn choices (CV 115) and in Athearn's case they are more limited than the stock SoundTraxx decoders. Below are links to the two Genesis specific locomotives, the GP15-1 and the just released GP38-2. Programming CV 115 to a value of 3 will set the GP38-2 for the Leslie RS5T. For the GP15-1, programming a value of 1 in CV 115 will set it to the S5T. GP38-2: http://soundtraxx.com/factory/images/athearn/pdf/Genesis/pre-2016/ath_gp38-2_ho.pdf GP15-1: http://soundtraxx.com/factory/images/athearn/pdf/Genesis/pre-2016/athearngen_gp15_ho.pdf Hope this helps!